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by PhilE
Sat Oct 21, 2017 9:33 am
Forum: Compute Module
Topic: 2 Cameras on compute module 3
Replies: 6
Views: 179

Re: 2 Cameras on compute module 3

Yes - you can put: dtoverlay=i2c-gpio in config.txt. By default it will use GPIOs 23 and 24, but you can change that with parameters: Name: i2c-gpio Info: Adds support for software i2c controller on gpio pins Load: dtoverlay=i2c-gpio,<param>=<val> Params: i2c_gpio_sda GPIO used for I2C data (default...
by PhilE
Thu Oct 19, 2017 10:24 am
Forum: Compute Module
Topic: CHANGING THE DEFAULT PIN CONFIGURATION of CM3
Replies: 11
Views: 356

Re: CHANGING THE DEFAULT PIN CONFIGURATION of CM3

The difference between dt-blob.dts and Device Tree is like the difference between a poem and a recipe - they are both written in the same language but with different purposes. dt-blob is a Broadcom-specific way of describing the GPIO and clock usage to the firmware, whereas Device Tree is a standard...
by PhilE
Wed Oct 18, 2017 12:32 pm
Forum: Compute Module
Topic: CHANGING THE DEFAULT PIN CONFIGURATION of CM3
Replies: 11
Views: 356

Re: CHANGING THE DEFAULT PIN CONFIGURATION of CM3

Also, dt-blob.dts is not Device Tree - it just uses the same syntax and compiler.
by PhilE
Tue Oct 17, 2017 10:00 am
Forum: Device Tree
Topic: phandle problems with machine driver
Replies: 2
Views: 148

Re: phandle problems with machine driver

There's a problem with this line: target = "i2c1"; The "target" property is used with phandles, while "target-path" is used with path strings, but the dtc compiler doesn't know this. The kernel is trying to interpret the string "i2c1" as a phandle and failing. What you meant to write is: target = <&...
by PhilE
Mon Oct 16, 2017 1:40 pm
Forum: Device Tree
Topic: how to include overlays for a multi-device hat?
Replies: 3
Views: 192

Re: how to include overlays for a multi-device hat?

There is no existing mechanism to do this. It wouldn't be too hard to implement one, but it would require either learning fdtlib (for dtbo files) or some text munging (for dts files). Working from source might be easier because then the compiler can work out the phandles (like pointers) for you, but...
by PhilE
Sun Oct 15, 2017 9:07 pm
Forum: Advanced users
Topic: program_gpio_bootmode broken on pi3b
Replies: 17
Views: 600

Re: program_gpio_bootmode broken on pi3b

I haven't been through the pin states for 39-43, but an unbootable Pi is a plausible outcome.

I would prefer to add a test for the invalid bootmode bits (19 clear and 20 set) which disables further attempts to program the GPIO bootmode bits.
by PhilE
Sun Oct 15, 2017 8:17 pm
Forum: Advanced users
Topic: program_gpio_bootmode broken on pi3b
Replies: 17
Views: 600

Re: program_gpio_bootmode broken on pi3b

pietjepuk1001, I think you've found a bug. The code which handles program_gpio_bootmode ends up setting the wrong bits in the OTP. Bit 19 (0x00080000) at offset 17 (and 18 for redundancy) enables the GPIO bootmode selection, while bit 20 (0x00100000) selects the high bank (39-43). By setting bit 20 ...
by PhilE
Fri Oct 13, 2017 9:05 am
Forum: Device Tree
Topic: How to wait for SPI1 being ready during boot?
Replies: 2
Views: 160

Re: How to wait for SPI1 being ready during boot?

All of the overlays specified in config.txt are applied before the ARM cores execute a single instruction. The kernel uses the information to load and configure devices drivers such as spi-bcm2835, which then enables the interface. A pause in the overlay application will make no difference at all to...
by PhilE
Thu Oct 12, 2017 3:32 pm
Forum: Compute Module
Topic: Compute Module IO Board Schematic
Replies: 2
Views: 162

Re: Compute Module IO Board Schematic

"NF" stands for "Not Fitted" - i.e. no component should be placed there, and it remains open-circuit.
"PP" is definitely a test point - I think it stands for "Probe Point".

Somebody else will have to explain the function of the circuit.
by PhilE
Thu Oct 12, 2017 3:20 pm
Forum: Device Tree
Topic: how to include overlays for a multi-device hat?
Replies: 3
Views: 192

Re: how to include overlays for a multi-device hat?

Overlays can be as large or small as you like. Aside from the header and fragment renumbering you can basically just concatenate several overlays to make a composite. The HAT EEPROM format was original designed to hold the overlay content, but the firmware now looks at the content of that section an...
by PhilE
Thu Oct 12, 2017 2:46 pm
Forum: Compute Module
Topic: Compute Module I2C not working (I2Cdetect)
Replies: 5
Views: 233

Re: Compute Module I2C not working (I2Cdetect)

The only other user is HAT EEPROMs, and that is disabled by default on CMs.
HAT EEPROMs are read once, long before the kernel starts, so that shouldn't be a problem on any platform.
by PhilE
Thu Oct 12, 2017 1:23 pm
Forum: Compute Module
Topic: Compute Module I2C not working (I2Cdetect)
Replies: 5
Views: 233

Re: Compute Module I2C not working (I2Cdetect)

1. Your hardware is probably wrong - do you have a pull-up on the bus? 2. . Is the I2C channel 1 the default available? Pardon? On everything but very early Pis, I2C1 is i2c_arm is i2c, while i2c0 is i2c_vc. Your answer may or may not be in that sentence, depending on what the question meant. 3. "dt...
by PhilE
Thu Oct 12, 2017 9:17 am
Forum: Device Tree
Topic: Loading Overlays Before GDM3 Login Screen
Replies: 4
Views: 707

Re: Loading Overlays Before GDM3 Login Screen

By the looks of it your overlay is the same, but you can download the official dtbo here.

I now think everything is working as it ought to except that GDM3 is blocking the power button in some way, but you could test it using Raspbian. I found this blog post - does it help?
by PhilE
Wed Oct 11, 2017 4:11 pm
Forum: Compute Module
Topic: Compute Module I2C not working (I2Cdetect)
Replies: 5
Views: 233

Re: Compute Module I2C not working (I2Cdetect)

I'm guessing your config.txt just says "dtparam=i2c=on", because if you'd written "dtparam=i2c_arm=on" you might have wondered why it says "i2c_arm" and not "i2c". The reason is that on each platform one of the i2c interfaces is nominally owned by the VideoCore VPU (usually i2c0), while the other (u...
by PhilE
Wed Oct 11, 2017 3:19 pm
Forum: Compute Module
Topic: UARTs on CM3
Replies: 5
Views: 628

Re: UARTs on CM3

UART1 is the mini-UART of the Pi3, a.k.a. ttyS0, while UART0 is ttyAMA0. Be aware that the core (VPU) clock frequency must not change while UART1 is in use, so you need to add core_freq=250 to config.txt.
by PhilE
Wed Oct 11, 2017 9:41 am
Forum: Device Tree
Topic: Making a Custom Device Tree - Not an Overlay
Replies: 1
Views: 245

Re: Making a Custom Device Tree - Not an Overlay

Assuming the problem is that the overlays don't change the device tree until after user logs in: That's an invalid assumption - unless you are talking about run-time overlay application using the Raspbian "dtoverlay" command, overlays are applied by the firmware before the kernel is started. As far...
by PhilE
Wed Oct 11, 2017 9:38 am
Forum: Device Tree
Topic: Loading Overlays Before GDM3 Login Screen
Replies: 4
Views: 707

Re: Loading Overlays Before GDM3 Login Screen

Overlays requested in config.txt are applied before the ARMs run their first instructions, so your problem lies elsewhere. Have you tried the gpio-shutdown overlay? pi@raspberrypi ~ $ dtoverlay -h gpio-shutdown Name: gpio-shutdown Info: Initiates a shutdown when GPIO pin changes. The given GPIO pin ...
by PhilE
Mon Oct 09, 2017 3:49 pm
Forum: Compute Module
Topic: Picture but no HDMI signal on pins
Replies: 6
Views: 364

Re: Picture but no HDMI signal on pins

How fast is your oscilloscope? The HDMI frequencies are in the 100s of MHz.
by PhilE
Mon Oct 09, 2017 9:20 am
Forum: Compute Module
Topic: [SOLVED] GPIOs 20 and 21 not switching on/off
Replies: 2
Views: 280

Re: GPIOs 20 and 21 not switching on/off

There is nothing special about GPIOs 20 & 21. They are in a different bank of 10 compared to the others, but that shouldn't be a problem. RPi.GPIO is hacky in that it writes directly to the hardware rather than using the Linux driver, but again it ought to work. I suggest using raspi-gpio (sudo apt-...
by PhilE
Mon Oct 09, 2017 9:08 am
Forum: Compute Module
Topic: 2 SD card on CM3L
Replies: 9
Views: 575

Re: 2 SD card on CM3L

The default bus width is 4 bits - bus=1 reduces that to 1. sdio_overclock=20 should have no effect at all - the value specifies which clock rate to use when the MMC subsystem asks for 50MHz, and it is only used if it is greater than 50.
by PhilE
Mon Oct 09, 2017 5:49 am
Forum: Compute Module
Topic: 2 SD card on CM3L
Replies: 9
Views: 575

Re: 2 SD card on CM3L

Overlays are loaded from /boot/overlays, so yes, you need to copy the compiled .dtbo file there. However, please use the new naming convention (*.dtbo):

Code: Select all

sudo mv sdio34.dtbo /boot/overlays/
by PhilE
Fri Oct 06, 2017 9:38 am
Forum: Compute Module
Topic: SD Card on computer module V3
Replies: 3
Views: 511

Re: SD Card on computer module V3

See this post for more details.
by PhilE
Fri Oct 06, 2017 9:13 am
Forum: Compute Module
Topic: 2 SD card on CM3L
Replies: 9
Views: 575

Re: 2 SD card on CM3L

Assuming you want the SD card to be secondary storage (i.e. not a boot device), you just need to edit the overlay source and change the pins from 22-27 to 34-39 and compile it. The source is here , and (assuming you rename it to sdio34-overlay.dts) you would compile it with: dtc -@ -I dts -O dtb -o ...
by PhilE
Thu Oct 05, 2017 6:40 pm
Forum: Device Tree
Topic: I2S clocks, GPCLK0
Replies: 44
Views: 1936

Re: I2S clocks, GPCLK0

I'm not sure it will make any difference to the behaviour, but modifying the codec is definitely not the right thing to do. As I've been trying to explain, codec drivers are supposed to be application neutral - all customisation should go in device tree declarations or the soundcard driver. I wouldn...

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