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sound: Support for Dion Audio LOCO-V2 DAC-AMP HAT
[mirror_ubuntu-zesty-kernel.git] / arch / arm / boot / dts / overlays / README
1 Introduction
2 ============
3
4 This directory contains Device Tree overlays. Device Tree makes it possible
5 to support many hardware configurations with a single kernel and without the
6 need to explicitly load or blacklist kernel modules. Note that this isn't a
7 "pure" Device Tree configuration (c.f. MACH_BCM2835) - some on-board devices
8 are still configured by the board support code, but the intention is to
9 eventually reach that goal.
10
11 On Raspberry Pi, Device Tree usage is controlled from /boot/config.txt. By
12 default, the Raspberry Pi kernel boots with device tree enabled. You can
13 completely disable DT usage (for now) by adding:
14
15 device_tree=
16
17 to your config.txt, which should cause your Pi to revert to the old way of
18 doing things after a reboot.
19
20 In /boot you will find a .dtb for each base platform. This describes the
21 hardware that is part of the Raspberry Pi board. The loader (start.elf and its
22 siblings) selects the .dtb file appropriate for the platform by name, and reads
23 it into memory. At this point, all of the optional interfaces (i2c, i2s, spi)
24 are disabled, but they can be enabled using Device Tree parameters:
25
26 dtparam=i2c=on,i2s=on,spi=on
27
28 However, this shouldn't be necessary in many use cases because loading an
29 overlay that requires one of those interfaces will cause it to be enabled
30 automatically, and it is advisable to only enable interfaces if they are
31 needed.
32
33 Configuring additional, optional hardware is done using Device Tree overlays
34 (see below).
35
36 raspi-config
37 ============
38
39 The Advanced Options section of the raspi-config utility can enable and disable
40 Device Tree use, as well as toggling the I2C and SPI interfaces. Note that it
41 is possible to both enable an interface and blacklist the driver, if for some
42 reason you should want to defer the loading.
43
44 Modules
45 =======
46
47 As well as describing the hardware, Device Tree also gives enough information
48 to allow suitable driver modules to be located and loaded, with the corollary
49 that unneeded modules are not loaded. As a result it should be possible to
50 remove lines from /etc/modules, and /etc/modprobe.d/raspi-blacklist.conf can
51 have its contents deleted (or commented out).
52
53 Using Overlays
54 ==============
55
56 Overlays are loaded using the "dtoverlay" directive. As an example, consider
57 the popular lirc-rpi module, the Linux Infrared Remote Control driver. In the
58 pre-DT world this would be loaded from /etc/modules, with an explicit
59 "modprobe lirc-rpi" command, or programmatically by lircd. With DT enabled,
60 this becomes a line in config.txt:
61
62 dtoverlay=lirc-rpi
63
64 This causes the file /boot/overlays/lirc-rpi.dtbo to be loaded. By
65 default it will use GPIOs 17 (out) and 18 (in), but this can be modified using
66 DT parameters:
67
68 dtoverlay=lirc-rpi,gpio_out_pin=17,gpio_in_pin=13
69
70 Parameters always have default values, although in some cases (e.g. "w1-gpio")
71 it is necessary to provided multiple overlays in order to get the desired
72 behaviour. See the list of overlays below for a description of the parameters
73 and their defaults.
74
75 The Overlay and Parameter Reference
76 ===================================
77
78 N.B. When editing this file, please preserve the indentation levels to make it
79 simple to parse programmatically. NO HARD TABS.
80
81
82 Name: <The base DTB>
83 Info: Configures the base Raspberry Pi hardware
84 Load: <loaded automatically>
85 Params:
86 audio Set to "on" to enable the onboard ALSA audio
87 interface (default "off")
88
89 i2c_arm Set to "on" to enable the ARM's i2c interface
90 (default "off")
91
92 i2c_vc Set to "on" to enable the i2c interface
93 usually reserved for the VideoCore processor
94 (default "off")
95
96 i2c An alias for i2c_arm
97
98 i2c_arm_baudrate Set the baudrate of the ARM's i2c interface
99 (default "100000")
100
101 i2c_vc_baudrate Set the baudrate of the VideoCore i2c interface
102 (default "100000")
103
104 i2c_baudrate An alias for i2c_arm_baudrate
105
106 i2s Set to "on" to enable the i2s interface
107 (default "off")
108
109 spi Set to "on" to enable the spi interfaces
110 (default "off")
111
112 random Set to "on" to enable the hardware random
113 number generator (default "on")
114
115 sd_overclock Clock (in MHz) to use when the MMC framework
116 requests 50MHz
117
118 sd_force_pio Disable DMA support for SD driver (default off)
119
120 sd_pio_limit Number of blocks above which to use DMA for
121 SD card (default 1)
122
123 sd_debug Enable debug output from SD driver (default off)
124
125 uart0 Set to "off" to disable uart0 (default "on")
126
127 uart1 Set to "on" or "off" to enable or disable uart1
128 (default varies)
129
130 watchdog Set to "on" to enable the hardware watchdog
131 (default "off")
132
133 act_led_trigger Choose which activity the LED tracks.
134 Use "heartbeat" for a nice load indicator.
135 (default "mmc")
136
137 act_led_activelow Set to "on" to invert the sense of the LED
138 (default "off")
139 N.B. For Pi3 see pi3-act-led overlay.
140
141 act_led_gpio Set which GPIO to use for the activity LED
142 (in case you want to connect it to an external
143 device)
144 (default "16" on a non-Plus board, "47" on a
145 Plus or Pi 2)
146 N.B. For Pi3 see pi3-act-led overlay.
147
148 pwr_led_trigger
149 pwr_led_activelow
150 pwr_led_gpio
151 As for act_led_*, but using the PWR LED.
152 Not available on Model A/B boards.
153
154 N.B. It is recommended to only enable those interfaces that are needed.
155 Leaving all interfaces enabled can lead to unwanted behaviour (i2c_vc
156 interfering with Pi Camera, I2S and SPI hogging GPIO pins, etc.)
157 Note also that i2c, i2c_arm and i2c_vc are aliases for the physical
158 interfaces i2c0 and i2c1. Use of the numeric variants is still possible
159 but deprecated because the ARM/VC assignments differ between board
160 revisions. The same board-specific mapping applies to i2c_baudrate,
161 and the other i2c baudrate parameters.
162
163
164 Name: adau1977-adc
165 Info: Overlay for activation of ADAU1977 ADC codec over I2C for control
166 and I2S for data.
167 Load: dtoverlay=adau1977-adc
168 Params: <None>
169
170
171 Name: adau7002-simple
172 Info: Overlay for the activation of ADAU7002 stereo PDM to I2S converter.
173 Load: dtoverlay=adau7002-simple,<param>=<val>
174 Params: card-name Override the default, "adau7002", card name.
175
176
177 Name: ads1015
178 Info: Overlay for activation of Texas Instruments ADS1015 ADC over I2C
179 Load: dtoverlay=ads1015,<param>=<val>
180 Params: addr I2C bus address of device. Set based on how the
181 addr pin is wired. (default=0x48 assumes addr
182 is pulled to GND)
183 cha_enable Enable virtual channel a. (default=true)
184 cha_cfg Set the configuration for virtual channel a.
185 (default=4 configures this channel for the
186 voltage at A0 with respect to GND)
187 cha_datarate Set the datarate (samples/sec) for this channel.
188 (default=4 sets 1600 sps)
189 cha_gain Set the gain of the Programmable Gain
190 Amplifier for this channel. (default=2 sets the
191 full scale of the channel to 2.048 Volts)
192
193 Channel (ch) parameters can be set for each enabled channel.
194 A maximum of 4 channels can be enabled (letters a thru d).
195 For more information refer to the device datasheet at:
196 http://www.ti.com/lit/ds/symlink/ads1015.pdf
197
198
199 Name: ads7846
200 Info: ADS7846 Touch controller
201 Load: dtoverlay=ads7846,<param>=<val>
202 Params: cs SPI bus Chip Select (default 1)
203 speed SPI bus speed (default 2MHz, max 3.25MHz)
204 penirq GPIO used for PENIRQ. REQUIRED
205 penirq_pull Set GPIO pull (default 0=none, 2=pullup)
206 swapxy Swap x and y axis
207 xmin Minimum value on the X axis (default 0)
208 ymin Minimum value on the Y axis (default 0)
209 xmax Maximum value on the X axis (default 4095)
210 ymax Maximum value on the Y axis (default 4095)
211 pmin Minimum reported pressure value (default 0)
212 pmax Maximum reported pressure value (default 65535)
213 xohms Touchpanel sensitivity (X-plate resistance)
214 (default 400)
215
216 penirq is required and usually xohms (60-100) has to be set as well.
217 Apart from that, pmax (255) and swapxy are also common.
218 The rest of the calibration can be done with xinput-calibrator.
219 See: github.com/notro/fbtft/wiki/FBTFT-on-Raspian
220 Device Tree binding document:
221 www.kernel.org/doc/Documentation/devicetree/bindings/input/ads7846.txt
222
223
224 Name: akkordion-iqdacplus
225 Info: Configures the Digital Dreamtime Akkordion Music Player (based on the
226 OEM IQAudIO DAC+ or DAC Zero module).
227 Load: dtoverlay=akkordion-iqdacplus,<param>=<val>
228 Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
229 Digital volume control. Enable with
230 dtoverlay=akkordion-iqdacplus,24db_digital_gain
231 (The default behaviour is that the Digital
232 volume control is limited to a maximum of
233 0dB. ie. it can attenuate but not provide
234 gain. For most users, this will be desired
235 as it will prevent clipping. By appending
236 the 24db_digital_gain parameter, the Digital
237 volume control will allow up to 24dB of
238 gain. If this parameter is enabled, it is the
239 responsibility of the user to ensure that
240 the Digital volume control is set to a value
241 that does not result in clipping/distortion!)
242
243
244 Name: allo-piano-dac-pcm512x-audio
245 Info: Configures the Allo Piano DAC (2.0/2.1) audio cards.
246 (NB. This initial support is for 2.0 channel audio ONLY! ie. stereo.
247 The subwoofer outputs on the Piano 2.1 are not currently supported!)
248 Load: dtoverlay=allo-piano-dac-pcm512x-audio,<param>
249 Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
250 Digital volume control.
251 (The default behaviour is that the Digital
252 volume control is limited to a maximum of
253 0dB. ie. it can attenuate but not provide
254 gain. For most users, this will be desired
255 as it will prevent clipping. By appending
256 the 24db_digital_gain parameter, the Digital
257 volume control will allow up to 24dB of
258 gain. If this parameter is enabled, it is the
259 responsibility of the user to ensure that
260 the Digital volume control is set to a value
261 that does not result in clipping/distortion!)
262
263
264 Name: at86rf233
265 Info: Configures the Atmel AT86RF233 802.15.4 low-power WPAN transceiver,
266 connected to spi0.0
267 Load: dtoverlay=at86rf233,<param>=<val>
268 Params: interrupt GPIO used for INT (default 23)
269 reset GPIO used for Reset (default 24)
270 sleep GPIO used for Sleep (default 25)
271 speed SPI bus speed in Hz (default 3000000)
272 trim Fine tuning of the internal capacitance
273 arrays (0=+0pF, 15=+4.5pF, default 15)
274
275
276 Name: audioinjector-wm8731-audio
277 Info: Configures the audioinjector.net audio add on soundcard
278 Load: dtoverlay=audioinjector-wm8731-audio
279 Params: <None>
280
281
282 Name: audremap
283 Info: Switches PWM sound output to pins 12 (Right) & 13 (Left)
284 Load: dtoverlay=audremap,<param>=<val>
285 Params: swap_lr Reverse the channel allocation, which will also
286 swap the audio jack outputs (default off)
287 enable_jack Don't switch off the audio jack output
288 (default off)
289
290
291 Name: bmp085_i2c-sensor
292 Info: This overlay is now deprecated - see i2c-sensor
293 Load: dtoverlay=bmp085_i2c-sensor
294 Params: <None>
295
296
297 Name: dht11
298 Info: Overlay for the DHT11/DHT21/DHT22 humidity/temperature sensors
299 Also sometimes found with the part number(s) AM230x.
300 Load: dtoverlay=dht11,<param>=<val>
301 Params: gpiopin GPIO connected to the sensor's DATA output.
302 (default 4)
303
304
305 Name: dionaudio-loco
306 Info: Configures the Dion Audio LOCO DAC-AMP
307 Load: dtoverlay=dionaudio-loco
308 Params: <None>
309
310
311 Name: dionaudio-loco-v2
312 Info: Configures the Dion Audio LOCO-V2 DAC-AMP
313 Load: dtoverlay=dionaudio-loco-v2,<param>=<val>
314 Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
315 Digital volume control. Enable with
316 "dtoverlay=hifiberry-dacplus,24db_digital_gain"
317 (The default behaviour is that the Digital
318 volume control is limited to a maximum of
319 0dB. ie. it can attenuate but not provide
320 gain. For most users, this will be desired
321 as it will prevent clipping. By appending
322 the 24dB_digital_gain parameter, the Digital
323 volume control will allow up to 24dB of
324 gain. If this parameter is enabled, it is the
325 responsibility of the user to ensure that
326 the Digital volume control is set to a value
327 that does not result in clipping/distortion!)
328
329
330 Name: dpi18
331 Info: Overlay for a generic 18-bit DPI display
332 This uses GPIOs 0-21 (so no I2C, uart etc.), and activates the output
333 2-3 seconds after the kernel has started.
334 Load: dtoverlay=dpi18
335 Params: <None>
336
337
338 Name: dpi24
339 Info: Overlay for a generic 24-bit DPI display
340 This uses GPIOs 0-27 (so no I2C, uart etc.), and activates the output
341 2-3 seconds after the kernel has started.
342 Load: dtoverlay=dpi24
343 Params: <None>
344
345
346 Name: dwc-otg
347 Info: Selects the dwc_otg USB controller driver which has fiq support. This
348 is the default on all except the Pi Zero which defaults to dwc2.
349 Load: dtoverlay=dwc-otg
350 Params: <None>
351
352
353 Name: dwc2
354 Info: Selects the dwc2 USB controller driver
355 Load: dtoverlay=dwc2,<param>=<val>
356 Params: dr_mode Dual role mode: "host", "peripheral" or "otg"
357
358 g-rx-fifo-size Size of rx fifo size in gadget mode
359
360 g-np-tx-fifo-size Size of non-periodic tx fifo size in gadget
361 mode
362
363 g-tx-fifo-size Size of periodic tx fifo per endpoint
364 (except ep0) in gadget mode
365
366
367 [ The ds1307-rtc overlay has been deleted. See i2c-rtc. ]
368
369
370 Name: enc28j60
371 Info: Overlay for the Microchip ENC28J60 Ethernet Controller on SPI0
372 Load: dtoverlay=enc28j60,<param>=<val>
373 Params: int_pin GPIO used for INT (default 25)
374
375 speed SPI bus speed (default 12000000)
376
377
378 Name: enc28j60-spi2
379 Info: Overlay for the Microchip ENC28J60 Ethernet Controller on SPI2
380 Load: dtoverlay=enc28j60-spi2,<param>=<val>
381 Params: int_pin GPIO used for INT (default 39)
382
383 speed SPI bus speed (default 12000000)
384
385
386 Name: gpio-ir
387 Info: Use GPIO pin as rc-core style infrared receiver input. The rc-core-
388 based gpio_ir_recv driver maps received keys directly to a
389 /dev/input/event* device, all decoding is done by the kernel - LIRC is
390 not required! The key mapping and other decoding parameters can be
391 configured by "ir-keytable" tool.
392 Load: dtoverlay=gpio-ir,<param>=<val>
393 Params: gpio_pin Input pin number. Default is 18.
394
395 gpio_pull Desired pull-up/down state (off, down, up)
396 Default is "down".
397
398 rc-map-name Default rc keymap (can also be changed by
399 ir-keytable), defaults to "rc-rc6-mce"
400
401
402 Name: gpio-poweroff
403 Info: Drives a GPIO high or low on poweroff (including halt)
404 Load: dtoverlay=gpio-poweroff,<param>=<val>
405 Params: gpiopin GPIO for signalling (default 26)
406
407 active_low Set if the power control device requires a
408 high->low transition to trigger a power-down.
409 Note that this will require the support of a
410 custom dt-blob.bin to prevent a power-down
411 during the boot process, and that a reboot
412 will also cause the pin to go low.
413
414
415 Name: hifiberry-amp
416 Info: Configures the HifiBerry Amp and Amp+ audio cards
417 Load: dtoverlay=hifiberry-amp
418 Params: <None>
419
420
421 Name: hifiberry-dac
422 Info: Configures the HifiBerry DAC audio card
423 Load: dtoverlay=hifiberry-dac
424 Params: <None>
425
426
427 Name: hifiberry-dacplus
428 Info: Configures the HifiBerry DAC+ audio card
429 Load: dtoverlay=hifiberry-dacplus,<param>=<val>
430 Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
431 Digital volume control. Enable with
432 "dtoverlay=hifiberry-dacplus,24db_digital_gain"
433 (The default behaviour is that the Digital
434 volume control is limited to a maximum of
435 0dB. ie. it can attenuate but not provide
436 gain. For most users, this will be desired
437 as it will prevent clipping. By appending
438 the 24dB_digital_gain parameter, the Digital
439 volume control will allow up to 24dB of
440 gain. If this parameter is enabled, it is the
441 responsibility of the user to ensure that
442 the Digital volume control is set to a value
443 that does not result in clipping/distortion!)
444 slave Force DAC+ Pro into slave mode, using Pi as
445 master for bit clock and frame clock.
446
447
448 Name: hifiberry-digi
449 Info: Configures the HifiBerry Digi and Digi+ audio card
450 Load: dtoverlay=hifiberry-digi
451 Params: <None>
452
453
454 Name: hifiberry-digi-pro
455 Info: Configures the HifiBerry Digi+ Pro audio card
456 Load: dtoverlay=hifiberry-digi-pro
457 Params: <None>
458
459
460 Name: hy28a
461 Info: HY28A - 2.8" TFT LCD Display Module by HAOYU Electronics
462 Default values match Texy's display shield
463 Load: dtoverlay=hy28a,<param>=<val>
464 Params: speed Display SPI bus speed
465
466 rotate Display rotation {0,90,180,270}
467
468 fps Delay between frame updates
469
470 debug Debug output level {0-7}
471
472 xohms Touchpanel sensitivity (X-plate resistance)
473
474 resetgpio GPIO used to reset controller
475
476 ledgpio GPIO used to control backlight
477
478
479 Name: hy28b
480 Info: HY28B - 2.8" TFT LCD Display Module by HAOYU Electronics
481 Default values match Texy's display shield
482 Load: dtoverlay=hy28b,<param>=<val>
483 Params: speed Display SPI bus speed
484
485 rotate Display rotation {0,90,180,270}
486
487 fps Delay between frame updates
488
489 debug Debug output level {0-7}
490
491 xohms Touchpanel sensitivity (X-plate resistance)
492
493 resetgpio GPIO used to reset controller
494
495 ledgpio GPIO used to control backlight
496
497
498 Name: i2c-bcm2708
499 Info: Fall back to the i2c_bcm2708 driver for the i2c_arm bus.
500 Load: dtoverlay=i2c-bcm2708
501 Params: <None>
502
503
504 Name: i2c-gpio
505 Info: Adds support for software i2c controller on gpio pins
506 Load: dtoverlay=i2c-gpio,<param>=<val>
507 Params: i2c_gpio_sda GPIO used for I2C data (default "23")
508
509 i2c_gpio_scl GPIO used for I2C clock (default "24")
510
511 i2c_gpio_delay_us Clock delay in microseconds
512 (default "2" = ~100kHz)
513
514
515 Name: i2c-mux
516 Info: Adds support for a number of I2C bus multiplexers on i2c_arm
517 Load: dtoverlay=i2c-mux,<param>=<val>
518 Params: pca9542 Select the NXP PCA9542 device
519
520 pca9545 Select the NXP PCA9545 device
521
522 pca9548 Select the NXP PCA9548 device
523
524 addr Change I2C address of the device (default 0x70)
525
526
527 [ The i2c-mux-pca9548a overlay has been deleted. See i2c-mux. ]
528
529
530 Name: i2c-pwm-pca9685a
531 Info: Adds support for an NXP PCA9685A I2C PWM controller on i2c_arm
532 Load: dtoverlay=i2c-pwm-pca9685a,<param>=<val>
533 Params: addr I2C address of PCA9685A (default 0x40)
534
535
536 Name: i2c-rtc
537 Info: Adds support for a number of I2C Real Time Clock devices
538 Load: dtoverlay=i2c-rtc,<param>=<val>
539 Params: abx80x Select one of the ABx80x family:
540 AB0801, AB0803, AB0804, AB0805,
541 AB1801, AB1803, AB1804, AB1805
542
543 ds1307 Select the DS1307 device
544
545 ds1339 Select the DS1339 device
546
547 ds3231 Select the DS3231 device
548
549 mcp7940x Select the MCP7940x device
550
551 mcp7941x Select the MCP7941x device
552
553 pcf2127 Select the PCF2127 device
554
555 pcf8523 Select the PCF8523 device
556
557 pcf8563 Select the PCF8563 device
558
559 trickle-diode-type Diode type for trickle charge - "standard" or
560 "schottky" (ABx80x only)
561
562 trickle-resistor-ohms Resistor value for trickle charge (DS1339,
563 ABx80x)
564
565 wakeup-source Specify that the RTC can be used as a wakeup
566 source
567
568
569 Name: i2c-sensor
570 Info: Adds support for a number of I2C barometric pressure and temperature
571 sensors on i2c_arm
572 Load: dtoverlay=i2c-sensor,<param>=<val>
573 Params: bmp085 Select the Bosch sensortronic BMP085
574
575 bmp280 Select the Bosch sensortronic BMP280
576
577 si7020 Select the Silicon Labs Si7013/20/21 humidity/
578 temperature sensor
579
580
581 Name: i2c0-bcm2708
582 Info: Enable the i2c_bcm2708 driver for the i2c0 bus. Not all pin combinations
583 are usable on all platforms.
584 Load: dtoverlay=i2c0-bcm2708,<param>=<val>
585 Params: sda0_pin GPIO pin for SDA0 (deprecated - use pins_*)
586 scl0_pin GPIO pin for SCL0 (deprecated - use pins_*)
587 pins_0_1 Use pins 0 and 1 (default)
588 pins_28_29 Use pins 28 and 29
589 pins_44_45 Use pins 44 and 45
590 pins_46_47 Use pins 46 and 47
591
592
593 Name: i2c1-bcm2708
594 Info: Enable the i2c_bcm2708 driver for the i2c1 bus
595 Load: dtoverlay=i2c1-bcm2708,<param>=<val>
596 Params: sda1_pin GPIO pin for SDA1 (2 or 44 - default 2)
597 scl1_pin GPIO pin for SCL1 (3 or 45 - default 3)
598 pin_func Alternative pin function (4 (alt0), 6 (alt2) -
599 default 4)
600
601
602 Name: i2s-gpio28-31
603 Info: move I2S function block to GPIO 28 to 31
604 Load: dtoverlay=i2s-gpio28-31
605 Params: <None>
606
607
608 Name: iqaudio-dac
609 Info: Configures the IQaudio DAC audio card
610 Load: dtoverlay=iqaudio-dac,<param>
611 Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
612 Digital volume control. Enable with
613 "dtoverlay=iqaudio-dac,24db_digital_gain"
614 (The default behaviour is that the Digital
615 volume control is limited to a maximum of
616 0dB. ie. it can attenuate but not provide
617 gain. For most users, this will be desired
618 as it will prevent clipping. By appending
619 the 24db_digital_gain parameter, the Digital
620 volume control will allow up to 24dB of
621 gain. If this parameter is enabled, it is the
622 responsibility of the user to ensure that
623 the Digital volume control is set to a value
624 that does not result in clipping/distortion!)
625
626
627 Name: iqaudio-dacplus
628 Info: Configures the IQaudio DAC+ audio card
629 Load: dtoverlay=iqaudio-dacplus,<param>=<val>
630 Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
631 Digital volume control. Enable with
632 "dtoverlay=iqaudio-dacplus,24db_digital_gain"
633 (The default behaviour is that the Digital
634 volume control is limited to a maximum of
635 0dB. ie. it can attenuate but not provide
636 gain. For most users, this will be desired
637 as it will prevent clipping. By appending
638 the 24db_digital_gain parameter, the Digital
639 volume control will allow up to 24dB of
640 gain. If this parameter is enabled, it is the
641 responsibility of the user to ensure that
642 the Digital volume control is set to a value
643 that does not result in clipping/distortion!)
644 auto_mute_amp If specified, unmute/mute the IQaudIO amp when
645 starting/stopping audio playback.
646 unmute_amp If specified, unmute the IQaudIO amp once when
647 the DAC driver module loads.
648
649
650 Name: iqaudio-digi-wm8804-audio
651 Info: Configures the IQAudIO Digi WM8804 audio card
652 Load: dtoverlay=iqaudio-digi-wm8804-audio,<param>=<val>
653 Params: card_name Override the default, "IQAudIODigi", card name.
654 dai_name Override the default, "IQAudIO Digi", dai name.
655 dai_stream_name Override the default, "IQAudIO Digi HiFi",
656 dai stream name.
657
658
659 Name: justboom-dac
660 Info: Configures the JustBoom DAC HAT, Amp HAT, DAC Zero and Amp Zero audio
661 cards
662 Load: dtoverlay=justboom-dac,<param>=<val>
663 Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
664 Digital volume control. Enable with
665 "dtoverlay=justboom-dac,24db_digital_gain"
666 (The default behaviour is that the Digital
667 volume control is limited to a maximum of
668 0dB. ie. it can attenuate but not provide
669 gain. For most users, this will be desired
670 as it will prevent clipping. By appending
671 the 24dB_digital_gain parameter, the Digital
672 volume control will allow up to 24dB of
673 gain. If this parameter is enabled, it is the
674 responsibility of the user to ensure that
675 the Digital volume control is set to a value
676 that does not result in clipping/distortion!)
677
678
679 Name: justboom-digi
680 Info: Configures the JustBoom Digi HAT and Digi Zero audio cards
681 Load: dtoverlay=justboom-digi
682 Params: <None>
683
684
685 Name: lirc-rpi
686 Info: Configures lirc-rpi (Linux Infrared Remote Control for Raspberry Pi)
687 Consult the module documentation for more details.
688 Load: dtoverlay=lirc-rpi,<param>=<val>
689 Params: gpio_out_pin GPIO for output (default "17")
690
691 gpio_in_pin GPIO for input (default "18")
692
693 gpio_in_pull Pull up/down/off on the input pin
694 (default "down")
695
696 sense Override the IR receive auto-detection logic:
697 "0" = force active-high
698 "1" = force active-low
699 "-1" = use auto-detection
700 (default "-1")
701
702 softcarrier Turn the software carrier "on" or "off"
703 (default "on")
704
705 invert "on" = invert the output pin (default "off")
706
707 debug "on" = enable additional debug messages
708 (default "off")
709
710
711 Name: mcp23017
712 Info: Configures the MCP23017 I2C GPIO expander
713 Load: dtoverlay=mcp23017,<param>=<val>
714 Params: gpiopin Gpio pin connected to the INTA output of the
715 MCP23017 (default: 4)
716
717 addr I2C address of the MCP23017 (default: 0x20)
718
719
720 Name: mcp23s17
721 Info: Configures the MCP23S08/17 SPI GPIO expanders.
722 If devices are present on SPI1 or SPI2, those interfaces must be enabled
723 with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
724 If interrupts are enabled for a device on a given CS# on a SPI bus, that
725 device must be the only one present on that SPI bus/CS#.
726 Load: dtoverlay=mcp23s17,<param>=<val>
727 Params: s08-spi<n>-<m>-present 4-bit integer, bitmap indicating MCP23S08
728 devices present on SPI<n>, CS#<m>
729
730 s17-spi<n>-<m>-present 8-bit integer, bitmap indicating MCP23S17
731 devices present on SPI<n>, CS#<m>
732
733 s08-spi<n>-<m>-int-gpio integer, enables interrupts on a single
734 MCP23S08 device on SPI<n>, CS#<m>, specifies
735 the GPIO pin to which INT output of MCP23S08
736 is connected.
737
738 s17-spi<n>-<m>-int-gpio integer, enables mirrored interrupts on a
739 single MCP23S17 device on SPI<n>, CS#<m>,
740 specifies the GPIO pin to which either INTA
741 or INTB output of MCP23S17 is connected.
742
743
744 Name: mcp2515-can0
745 Info: Configures the MCP2515 CAN controller on spi0.0
746 Load: dtoverlay=mcp2515-can0,<param>=<val>
747 Params: oscillator Clock frequency for the CAN controller (Hz)
748
749 spimaxfrequency Maximum SPI frequence (Hz)
750
751 interrupt GPIO for interrupt signal
752
753
754 Name: mcp2515-can1
755 Info: Configures the MCP2515 CAN controller on spi0.1
756 Load: dtoverlay=mcp2515-can1,<param>=<val>
757 Params: oscillator Clock frequency for the CAN controller (Hz)
758
759 spimaxfrequency Maximum SPI frequence (Hz)
760
761 interrupt GPIO for interrupt signal
762
763
764 Name: mcp3008
765 Info: Configures MCP3008 A/D converters
766 For devices on spi1 or spi2, the interfaces should be enabled
767 with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
768 Load: dtoverlay=mcp3008,<param>[=<val>]
769 Params: spi<n>-<m>-present boolean, configure device at spi<n>, cs<m>
770 spi<n>-<m>-speed integer, set the spi bus speed for this device
771
772
773 Name: midi-uart0
774 Info: Configures UART0 (ttyAMA0) so that a requested 38.4kbaud actually gets
775 31.25kbaud, the frequency required for MIDI
776 Load: dtoverlay=midi-uart0
777 Params: <None>
778
779
780 Name: mmc
781 Info: Selects the bcm2835-mmc SD/MMC driver, optionally with overclock
782 Load: dtoverlay=mmc,<param>=<val>
783 Params: overclock_50 Clock (in MHz) to use when the MMC framework
784 requests 50MHz
785
786
787 Name: mz61581
788 Info: MZ61581 display by Tontec
789 Load: dtoverlay=mz61581,<param>=<val>
790 Params: speed Display SPI bus speed
791
792 rotate Display rotation {0,90,180,270}
793
794 fps Delay between frame updates
795
796 txbuflen Transmit buffer length (default 32768)
797
798 debug Debug output level {0-7}
799
800 xohms Touchpanel sensitivity (X-plate resistance)
801
802
803 [ The pcf2127-rtc overlay has been deleted. See i2c-rtc. ]
804
805
806 [ The pcf8523-rtc overlay has been deleted. See i2c-rtc. ]
807
808
809 [ The pcf8563-rtc overlay has been deleted. See i2c-rtc. ]
810
811
812 Name: pi3-act-led
813 Info: Pi3 uses a GPIO expander to drive the LEDs which can only be accessed
814 from the VPU. There is a special driver for this with a separate DT
815 node, which has the unfortunate consequence of breaking the
816 act_led_gpio and act_led_activelow dtparams.
817 This overlay changes the GPIO controller back to the standard one and
818 restores the dtparams.
819 Load: dtoverlay=pi3-act-led,<param>=<val>
820 Params: activelow Set to "on" to invert the sense of the LED
821 (default "off")
822
823 gpio Set which GPIO to use for the activity LED
824 (in case you want to connect it to an external
825 device)
826 REQUIRED
827
828
829 Name: pi3-disable-bt
830 Info: Disable Pi3 Bluetooth and restore UART0/ttyAMA0 over GPIOs 14 & 15
831 N.B. To disable the systemd service that initialises the modem so it
832 doesn't use the UART, use 'sudo systemctl disable hciuart'.
833 Load: dtoverlay=pi3-disable-bt
834 Params: <None>
835
836
837 Name: pi3-disable-wifi
838 Info: Disable Pi3 onboard WiFi
839 Load: dtoverlay=pi3-disable-wifi
840 Params: <None>
841
842
843 Name: pi3-miniuart-bt
844 Info: Switch Pi3 Bluetooth function to use the mini-UART (ttyS0) and restore
845 UART0/ttyAMA0 over GPIOs 14 & 15. Note that this may reduce the maximum
846 usable baudrate.
847 N.B. It is also necessary to edit /lib/systemd/system/hciuart.service
848 and replace ttyAMA0 with ttyS0, unless you have a system with udev rules
849 that create /dev/serial0 and /dev/serial1, in which case use
850 /dev/serial1 instead because it will always be correct. Furthermore,
851 you must also set core_freq=250 in config.txt or the miniuart will not
852 work.
853 Load: dtoverlay=pi3-miniuart-bt
854 Params: <None>
855
856
857 Name: piscreen
858 Info: PiScreen display by OzzMaker.com
859 Load: dtoverlay=piscreen,<param>=<val>
860 Params: speed Display SPI bus speed
861
862 rotate Display rotation {0,90,180,270}
863
864 fps Delay between frame updates
865
866 debug Debug output level {0-7}
867
868 xohms Touchpanel sensitivity (X-plate resistance)
869
870
871 Name: piscreen2r
872 Info: PiScreen 2 with resistive TP display by OzzMaker.com
873 Load: dtoverlay=piscreen2r,<param>=<val>
874 Params: speed Display SPI bus speed
875
876 rotate Display rotation {0,90,180,270}
877
878 fps Delay between frame updates
879
880 debug Debug output level {0-7}
881
882 xohms Touchpanel sensitivity (X-plate resistance)
883
884
885 Name: pisound
886 Info: Configures the Blokas Labs pisound card
887 Load: dtoverlay=pisound
888 Params: <None>
889
890
891 Name: pitft22
892 Info: Adafruit PiTFT 2.2" screen
893 Load: dtoverlay=pitft22,<param>=<val>
894 Params: speed Display SPI bus speed
895
896 rotate Display rotation {0,90,180,270}
897
898 fps Delay between frame updates
899
900 debug Debug output level {0-7}
901
902
903 Name: pitft28-capacitive
904 Info: Adafruit PiTFT 2.8" capacitive touch screen
905 Load: dtoverlay=pitft28-capacitive,<param>=<val>
906 Params: speed Display SPI bus speed
907
908 rotate Display rotation {0,90,180,270}
909
910 fps Delay between frame updates
911
912 debug Debug output level {0-7}
913
914 touch-sizex Touchscreen size x (default 240)
915
916 touch-sizey Touchscreen size y (default 320)
917
918 touch-invx Touchscreen inverted x axis
919
920 touch-invy Touchscreen inverted y axis
921
922 touch-swapxy Touchscreen swapped x y axis
923
924
925 Name: pitft28-resistive
926 Info: Adafruit PiTFT 2.8" resistive touch screen
927 Load: dtoverlay=pitft28-resistive,<param>=<val>
928 Params: speed Display SPI bus speed
929
930 rotate Display rotation {0,90,180,270}
931
932 fps Delay between frame updates
933
934 debug Debug output level {0-7}
935
936
937 Name: pitft35-resistive
938 Info: Adafruit PiTFT 3.5" resistive touch screen
939 Load: dtoverlay=pitft35-resistive,<param>=<val>
940 Params: speed Display SPI bus speed
941
942 rotate Display rotation {0,90,180,270}
943
944 fps Delay between frame updates
945
946 debug Debug output level {0-7}
947
948
949 Name: pps-gpio
950 Info: Configures the pps-gpio (pulse-per-second time signal via GPIO).
951 Load: dtoverlay=pps-gpio,<param>=<val>
952 Params: gpiopin Input GPIO (default "18")
953 assert_falling_edge When present, assert is indicated by a falling
954 edge, rather than by a rising edge
955
956
957 Name: pwm
958 Info: Configures a single PWM channel
959 Legal pin,function combinations for each channel:
960 PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
961 PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1)
962 N.B.:
963 1) Pin 18 is the only one available on all platforms, and
964 it is the one used by the I2S audio interface.
965 Pins 12 and 13 might be better choices on an A+, B+ or Pi2.
966 2) The onboard analogue audio output uses both PWM channels.
967 3) So be careful mixing audio and PWM.
968 4) Currently the clock must have been enabled and configured
969 by other means.
970 Load: dtoverlay=pwm,<param>=<val>
971 Params: pin Output pin (default 18) - see table
972 func Pin function (default 2 = Alt5) - see above
973 clock PWM clock frequency (informational)
974
975
976 Name: pwm-2chan
977 Info: Configures both PWM channels
978 Legal pin,function combinations for each channel:
979 PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
980 PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1)
981 N.B.:
982 1) Pin 18 is the only one available on all platforms, and
983 it is the one used by the I2S audio interface.
984 Pins 12 and 13 might be better choices on an A+, B+ or Pi2.
985 2) The onboard analogue audio output uses both PWM channels.
986 3) So be careful mixing audio and PWM.
987 4) Currently the clock must have been enabled and configured
988 by other means.
989 Load: dtoverlay=pwm-2chan,<param>=<val>
990 Params: pin Output pin (default 18) - see table
991 pin2 Output pin for other channel (default 19)
992 func Pin function (default 2 = Alt5) - see above
993 func2 Function for pin2 (default 2 = Alt5)
994 clock PWM clock frequency (informational)
995
996
997 Name: qca7000
998 Info: I2SE's Evaluation Board for PLC Stamp micro
999 Load: dtoverlay=qca7000,<param>=<val>
1000 Params: int_pin GPIO pin for interrupt signal (default 23)
1001
1002 speed SPI bus speed (default 12 MHz)
1003
1004
1005 Name: raspidac3
1006 Info: Configures the RaspiDAV Rev.3x audio card
1007 Load: dtoverlay=raspidac3
1008 Params: <None>
1009
1010
1011 Name: rpi-backlight
1012 Info: Raspberry Pi official display backlight driver
1013 Load: dtoverlay=rpi-backlight
1014 Params: <None>
1015
1016
1017 Name: rpi-cirrus-wm5102
1018 Info: Configures the Cirrus Logic Audio Card
1019 Load: dtoverlay=rpi-cirrus-wm5102
1020 Params: <None>
1021
1022
1023 Name: rpi-dac
1024 Info: Configures the RPi DAC audio card
1025 Load: dtoverlay=rpi-dac
1026 Params: <None>
1027
1028
1029 Name: rpi-display
1030 Info: RPi-Display - 2.8" Touch Display by Watterott
1031 Load: dtoverlay=rpi-display,<param>=<val>
1032 Params: speed Display SPI bus speed
1033 rotate Display rotation {0,90,180,270}
1034 fps Delay between frame updates
1035 debug Debug output level {0-7}
1036 xohms Touchpanel sensitivity (X-plate resistance)
1037 swapxy Swap x and y axis
1038
1039
1040 Name: rpi-ft5406
1041 Info: Official Raspberry Pi display touchscreen
1042 Load: dtoverlay=rpi-ft5406
1043 Params: <None>
1044
1045
1046 Name: rpi-proto
1047 Info: Configures the RPi Proto audio card
1048 Load: dtoverlay=rpi-proto
1049 Params: <None>
1050
1051
1052 Name: rpi-sense
1053 Info: Raspberry Pi Sense HAT
1054 Load: dtoverlay=rpi-sense
1055 Params: <None>
1056
1057
1058 Name: rra-digidac1-wm8741-audio
1059 Info: Configures the Red Rocks Audio DigiDAC1 soundcard
1060 Load: dtoverlay=rra-digidac1-wm8741-audio
1061 Params: <None>
1062
1063
1064 Name: sc16is750-i2c
1065 Info: Overlay for the NXP SC16IS750 UART with I2C Interface
1066 Enables the chip on I2C1 at 0x48. To select another address,
1067 please refer to table 10 in reference manual.
1068
1069 Load: dtoverlay=sc16is750-i2c,<param>=<val>
1070 Params: int_pin GPIO used for IRQ (default 24)
1071 addr Address (default 0x48)
1072
1073
1074 Name: sc16is752-spi1
1075 Info: Overlay for the NXP SC16IS752 Dual UART with SPI Interface
1076 Enables the chip on SPI1.
1077 N.B.: spi1 is only accessible on devices with a 40pin header, eg:
1078 A+, B+, Zero and PI2 B; as well as the Compute Module.
1079
1080 Load: dtoverlay=sc16is752-spi1,<param>=<val>
1081 Params: int_pin GPIO used for IRQ (default 24)
1082
1083
1084 Name: sdhost
1085 Info: Selects the bcm2835-sdhost SD/MMC driver, optionally with overclock.
1086 N.B. This overlay is designed for situations where the mmc driver is
1087 the default, so it disables the other (mmc) interface - this will kill
1088 WiFi on a Pi3. If this isn't what you want, either use the sdtweak
1089 overlay or the new sd_* dtparams of the base DTBs.
1090 Load: dtoverlay=sdhost,<param>=<val>
1091 Params: overclock_50 Clock (in MHz) to use when the MMC framework
1092 requests 50MHz
1093
1094 force_pio Disable DMA support (default off)
1095
1096 pio_limit Number of blocks above which to use DMA
1097 (default 1)
1098
1099 debug Enable debug output (default off)
1100
1101
1102 Name: sdio
1103 Info: Selects the bcm2835-sdhost SD/MMC driver, optionally with overclock,
1104 and enables SDIO via GPIOs 22-27.
1105 Load: dtoverlay=sdio,<param>=<val>
1106 Params: overclock_50 SD Clock (in MHz) to use when the MMC framework
1107 requests 50MHz
1108
1109 sdio_overclock SDIO Clock (in MHz) to use when the MMC
1110 framework requests 50MHz
1111
1112 force_pio Disable DMA support (default off)
1113
1114 pio_limit Number of blocks above which to use DMA
1115 (default 1)
1116
1117 debug Enable debug output (default off)
1118
1119 poll_once Disable SDIO-device polling every second
1120 (default on: polling once at boot-time)
1121
1122 bus_width Set the SDIO host bus width (default 4 bits)
1123
1124
1125 Name: sdio-1bit
1126 Info: Selects the bcm2835-sdhost SD/MMC driver, optionally with overclock,
1127 and enables 1-bit SDIO via GPIOs 22-25.
1128 Load: dtoverlay=sdio-1bit,<param>=<val>
1129 Params: overclock_50 SD Clock (in MHz) to use when the MMC framework
1130 requests 50MHz
1131
1132 sdio_overclock SDIO Clock (in MHz) to use when the MMC
1133 framework requests 50MHz
1134
1135 force_pio Disable DMA support (default off)
1136
1137 pio_limit Number of blocks above which to use DMA
1138 (default 1)
1139
1140 debug Enable debug output (default off)
1141
1142 poll_once Disable SDIO-device polling every second
1143 (default on: polling once at boot-time)
1144
1145
1146 Name: sdtweak
1147 Info: Tunes the bcm2835-sdhost SD/MMC driver
1148 N.B. This functionality is now available via the sd_* dtparams in the
1149 base DTB.
1150 Load: dtoverlay=sdtweak,<param>=<val>
1151 Params: overclock_50 Clock (in MHz) to use when the MMC framework
1152 requests 50MHz
1153
1154 force_pio Disable DMA support (default off)
1155
1156 pio_limit Number of blocks above which to use DMA
1157 (default 1)
1158
1159 debug Enable debug output (default off)
1160
1161
1162 Name: smi
1163 Info: Enables the Secondary Memory Interface peripheral. Uses GPIOs 2-25!
1164 Load: dtoverlay=smi
1165 Params: <None>
1166
1167
1168 Name: smi-dev
1169 Info: Enables the userspace interface for the SMI driver
1170 Load: dtoverlay=smi-dev
1171 Params: <None>
1172
1173
1174 Name: smi-nand
1175 Info: Enables access to NAND flash via the SMI interface
1176 Load: dtoverlay=smi-nand
1177 Params: <None>
1178
1179
1180 Name: spi-gpio35-39
1181 Info: Move SPI function block to GPIO 35 to 39
1182 Load: dtoverlay=spi-gpio35-39
1183 Params: <None>
1184
1185
1186 Name: spi-rtc
1187 Info: Adds support for a number of SPI Real Time Clock devices
1188 Load: dtoverlay=spi-rtc,<param>=<val>
1189 Params: pcf2123 Select the PCF2123 device
1190
1191
1192 Name: spi0-cs
1193 Info: Allows the (software) CS pins for SPI0 to be changed
1194 Load: dtoverlay=spi0-cs,<param>=<val>
1195 Params: cs0_pin GPIO pin for CS0 (default 8)
1196 cs1_pin GPIO pin for CS1 (default 7)
1197
1198
1199 Name: spi0-hw-cs
1200 Info: Re-enables hardware CS/CE (chip selects) for SPI0
1201 Load: dtoverlay=spi0-hw-cs
1202 Params: <None>
1203
1204
1205 Name: spi1-1cs
1206 Info: Enables spi1 with a single chip select (CS) line and associated spidev
1207 dev node. The gpio pin number for the CS line and spidev device node
1208 creation are configurable.
1209 N.B.: spi1 is only accessible on devices with a 40pin header, eg:
1210 A+, B+, Zero and PI2 B; as well as the Compute Module.
1211 Load: dtoverlay=spi1-1cs,<param>=<val>
1212 Params: cs0_pin GPIO pin for CS0 (default 18 - BCM SPI1_CE0).
1213 cs0_spidev Set to 'disabled' to stop the creation of a
1214 userspace device node /dev/spidev1.0 (default
1215 is 'okay' or enabled).
1216
1217
1218 Name: spi1-2cs
1219 Info: Enables spi1 with two chip select (CS) lines and associated spidev
1220 dev nodes. The gpio pin numbers for the CS lines and spidev device node
1221 creation are configurable.
1222 N.B.: spi1 is only accessible on devices with a 40pin header, eg:
1223 A+, B+, Zero and PI2 B; as well as the Compute Module.
1224 Load: dtoverlay=spi1-2cs,<param>=<val>
1225 Params: cs0_pin GPIO pin for CS0 (default 18 - BCM SPI1_CE0).
1226 cs1_pin GPIO pin for CS1 (default 17 - BCM SPI1_CE1).
1227 cs0_spidev Set to 'disabled' to stop the creation of a
1228 userspace device node /dev/spidev1.0 (default
1229 is 'okay' or enabled).
1230 cs1_spidev Set to 'disabled' to stop the creation of a
1231 userspace device node /dev/spidev1.1 (default
1232 is 'okay' or enabled).
1233
1234
1235 Name: spi1-3cs
1236 Info: Enables spi1 with three chip select (CS) lines and associated spidev
1237 dev nodes. The gpio pin numbers for the CS lines and spidev device node
1238 creation are configurable.
1239 N.B.: spi1 is only accessible on devices with a 40pin header, eg:
1240 A+, B+, Zero and PI2 B; as well as the Compute Module.
1241 Load: dtoverlay=spi1-3cs,<param>=<val>
1242 Params: cs0_pin GPIO pin for CS0 (default 18 - BCM SPI1_CE0).
1243 cs1_pin GPIO pin for CS1 (default 17 - BCM SPI1_CE1).
1244 cs2_pin GPIO pin for CS2 (default 16 - BCM SPI1_CE2).
1245 cs0_spidev Set to 'disabled' to stop the creation of a
1246 userspace device node /dev/spidev1.0 (default
1247 is 'okay' or enabled).
1248 cs1_spidev Set to 'disabled' to stop the creation of a
1249 userspace device node /dev/spidev1.1 (default
1250 is 'okay' or enabled).
1251 cs2_spidev Set to 'disabled' to stop the creation of a
1252 userspace device node /dev/spidev1.2 (default
1253 is 'okay' or enabled).
1254
1255
1256 Name: spi2-1cs
1257 Info: Enables spi2 with a single chip select (CS) line and associated spidev
1258 dev node. The gpio pin number for the CS line and spidev device node
1259 creation are configurable.
1260 N.B.: spi2 is only accessible with the Compute Module.
1261 Load: dtoverlay=spi2-1cs,<param>=<val>
1262 Params: cs0_pin GPIO pin for CS0 (default 43 - BCM SPI2_CE0).
1263 cs0_spidev Set to 'disabled' to stop the creation of a
1264 userspace device node /dev/spidev2.0 (default
1265 is 'okay' or enabled).
1266
1267
1268 Name: spi2-2cs
1269 Info: Enables spi2 with two chip select (CS) lines and associated spidev
1270 dev nodes. The gpio pin numbers for the CS lines and spidev device node
1271 creation are configurable.
1272 N.B.: spi2 is only accessible with the Compute Module.
1273 Load: dtoverlay=spi2-2cs,<param>=<val>
1274 Params: cs0_pin GPIO pin for CS0 (default 43 - BCM SPI2_CE0).
1275 cs1_pin GPIO pin for CS1 (default 44 - BCM SPI2_CE1).
1276 cs0_spidev Set to 'disabled' to stop the creation of a
1277 userspace device node /dev/spidev2.0 (default
1278 is 'okay' or enabled).
1279 cs1_spidev Set to 'disabled' to stop the creation of a
1280 userspace device node /dev/spidev2.1 (default
1281 is 'okay' or enabled).
1282
1283
1284 Name: spi2-3cs
1285 Info: Enables spi2 with three chip select (CS) lines and associated spidev
1286 dev nodes. The gpio pin numbers for the CS lines and spidev device node
1287 creation are configurable.
1288 N.B.: spi2 is only accessible with the Compute Module.
1289 Load: dtoverlay=spi2-3cs,<param>=<val>
1290 Params: cs0_pin GPIO pin for CS0 (default 43 - BCM SPI2_CE0).
1291 cs1_pin GPIO pin for CS1 (default 44 - BCM SPI2_CE1).
1292 cs2_pin GPIO pin for CS2 (default 45 - BCM SPI2_CE2).
1293 cs0_spidev Set to 'disabled' to stop the creation of a
1294 userspace device node /dev/spidev2.0 (default
1295 is 'okay' or enabled).
1296 cs1_spidev Set to 'disabled' to stop the creation of a
1297 userspace device node /dev/spidev2.1 (default
1298 is 'okay' or enabled).
1299 cs2_spidev Set to 'disabled' to stop the creation of a
1300 userspace device node /dev/spidev2.2 (default
1301 is 'okay' or enabled).
1302
1303
1304 Name: tinylcd35
1305 Info: 3.5" Color TFT Display by www.tinylcd.com
1306 Options: Touch, RTC, keypad
1307 Load: dtoverlay=tinylcd35,<param>=<val>
1308 Params: speed Display SPI bus speed
1309
1310 rotate Display rotation {0,90,180,270}
1311
1312 fps Delay between frame updates
1313
1314 debug Debug output level {0-7}
1315
1316 touch Enable touch panel
1317
1318 touchgpio Touch controller IRQ GPIO
1319
1320 xohms Touchpanel: Resistance of X-plate in ohms
1321
1322 rtc-pcf PCF8563 Real Time Clock
1323
1324 rtc-ds DS1307 Real Time Clock
1325
1326 keypad Enable keypad
1327
1328 Examples:
1329 Display with touchpanel, PCF8563 RTC and keypad:
1330 dtoverlay=tinylcd35,touch,rtc-pcf,keypad
1331 Old touch display:
1332 dtoverlay=tinylcd35,touch,touchgpio=3
1333
1334
1335 Name: uart1
1336 Info: Enable uart1 in place of uart0
1337 Load: dtoverlay=uart1,<param>=<val>
1338 Params: txd1_pin GPIO pin for TXD1 (14, 32 or 40 - default 14)
1339
1340 rxd1_pin GPIO pin for RXD1 (15, 33 or 41 - default 15)
1341
1342
1343 Name: vc4-fkms-v3d
1344 Info: Enable Eric Anholt's DRM VC4 V3D driver on top of the dispmanx
1345 display stack.
1346 Load: dtoverlay=vc4-fkms-v3d,<param>
1347 Params: cma-256 CMA is 256MB, 256MB-aligned (needs 1GB)
1348 cma-192 CMA is 192MB, 256MB-aligned (needs 1GB)
1349 cma-128 CMA is 128MB, 128MB-aligned
1350 cma-96 CMA is 96MB, 128MB-aligned
1351 cma-64 CMA is 64MB, 64MB-aligned
1352
1353
1354 Name: vc4-kms-v3d
1355 Info: Enable Eric Anholt's DRM VC4 HDMI/HVS/V3D driver. Running startx or
1356 booting to GUI while this overlay is in use will cause interesting
1357 lockups.
1358 Load: dtoverlay=vc4-kms-v3d,<param>
1359 Params: cma-256 CMA is 256MB, 256MB-aligned (needs 1GB)
1360 cma-192 CMA is 192MB, 256MB-aligned (needs 1GB)
1361 cma-128 CMA is 128MB, 128MB-aligned
1362 cma-96 CMA is 96MB, 128MB-aligned
1363 cma-64 CMA is 64MB, 64MB-aligned
1364
1365
1366 Name: vga666
1367 Info: Overlay for the Fen Logic VGA666 board
1368 This uses GPIOs 2-21 (so no I2C), and activates the output 2-3 seconds
1369 after the kernel has started.
1370 Load: dtoverlay=vga666
1371 Params: <None>
1372
1373
1374 Name: w1-gpio
1375 Info: Configures the w1-gpio Onewire interface module.
1376 Use this overlay if you *don't* need a GPIO to drive an external pullup.
1377 Load: dtoverlay=w1-gpio,<param>=<val>
1378 Params: gpiopin GPIO for I/O (default "4")
1379
1380 pullup Non-zero, "on", or "y" to enable the parasitic
1381 power (2-wire, power-on-data) feature
1382
1383
1384 Name: w1-gpio-pullup
1385 Info: Configures the w1-gpio Onewire interface module.
1386 Use this overlay if you *do* need a GPIO to drive an external pullup.
1387 Load: dtoverlay=w1-gpio-pullup,<param>=<val>
1388 Params: gpiopin GPIO for I/O (default "4")
1389
1390 pullup Non-zero, "on", or "y" to enable the parasitic
1391 power (2-wire, power-on-data) feature
1392
1393 extpullup GPIO for external pullup (default "5")
1394
1395
1396 Name: wittypi
1397 Info: Configures the wittypi RTC module.
1398 Load: dtoverlay=wittypi,<param>=<val>
1399 Params: led_gpio GPIO for LED (default "17")
1400 led_trigger Choose which activity the LED tracks (default
1401 "default-on")
1402
1403
1404 Troubleshooting
1405 ===============
1406
1407 If you are experiencing problems that you think are DT-related, enable DT
1408 diagnostic output by adding this to /boot/config.txt:
1409
1410 dtdebug=on
1411
1412 and rebooting. Then run:
1413
1414 sudo vcdbg log msg
1415
1416 and look for relevant messages.
1417
1418 Further reading
1419 ===============
1420
1421 This is only meant to be a quick introduction to the subject of Device Tree on
1422 Raspberry Pi. There is a more complete explanation here:
1423
1424 http://www.raspberrypi.org/documentation/configuration/device-tree.md
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