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by PhilE
Tue Jul 17, 2018 4:18 pm
Forum: Compute Module
Topic: Help getting DPI touchscreen to work on Compute Module 3
Replies: 7
Views: 135

Re: Help getting DPI touchscreen to work on Compute Module 3

Problem 1: Either you don't have the i2c_dev module loaded, or you don't have any enabled I2C buses or both. Running lsmod will tell you if i2c_dev is loaded - if not, "sudo modprobe i2c_dev" and "ls /dev/i2c*". Problem 2: Your overlay changes the pins claimed on behalf of i2c1, but sets the pin fun...
by PhilE
Tue Jul 17, 2018 3:18 pm
Forum: Compute Module
Topic: Help getting DPI touchscreen to work on Compute Module 3
Replies: 7
Views: 135

Re: Help getting DPI touchscreen to work on Compute Module 3

The official Raspberry Pi touchscreen lives on I2C0, which is reserved for the firmware on most Pis, and is polled by the firmware; the kernel driver retrieves the touch event data from the firmware, not from I2C. Let's go back to basics. What do the following commands return? $ i2cdetect -y 0 $ i2c...
by PhilE
Mon Jul 16, 2018 10:40 am
Forum: Device Tree
Topic: Connecting external raw nand using GPIO - RPI3b
Replies: 9
Views: 190

Re: Connecting external raw nand using GPIO - RPI3b

The GPIO alternate function assignments are listed on page 102 of the BCM2835 ARM Peripherals guide.
by PhilE
Mon Jul 16, 2018 10:00 am
Forum: Device Tree
Topic: Connecting external raw nand using GPIO - RPI3b
Replies: 9
Views: 190

Re: Connecting external raw nand using GPIO - RPI3b

The post is a bit ambiguous, but the smi-nand overlay (at least as it is now) is standalone. I don't know whether the SMI interface can multiplex address and data on the same lines - that's clearly not the way this overlay is expected to be used. I've pinged LukeW, the author of the driver, in case ...
by PhilE
Mon Jul 16, 2018 8:39 am
Forum: Device Tree
Topic: Connecting external raw nand using GPIO - RPI3b
Replies: 9
Views: 190

Re: Connecting external raw nand using GPIO - RPI3b

I have been only dimly aware of SMI - I've used I2C, SPI, SD, but not SMI - so when you mentioned NAND I didn't immediately think of it. But yes - the BCM2835 has an SMI interface, and there is a driver and overlay for it in the RPi kernel trees. There is also a NAND adaptation layer driver and over...
by PhilE
Fri Jul 13, 2018 3:24 pm
Forum: Compute Module
Topic: [SOLVED] PWM0 on GPIO40 - can't export due to permissions?
Replies: 2
Views: 79

Re: PWM0 on GPIO40 - can't export due to permissions?

I think your use of sudo is ineffective because of the way shell redirection works. When you write: $ sudo echo 0 > export the shell splits the line at the '>' and passes everthing on the left to sudo, redirecting the output to 'export'. That sounds okay, except that the sudo command and the file ac...
by PhilE
Fri Jul 13, 2018 6:40 am
Forum: Compute Module
Topic: CM3 eMMC with u-boot not working
Replies: 4
Views: 144

Re: CM3 eMMC with u-boot not working

There should be no doubt - BCM2837 is a 64-bit capable SoC, but the standard Raspberry Pi kernel runs in 32-bit mode. While there are some nice aspects of going 64-bit, there is no clear performance benefit to justify supporting a third kernel variant. Other distributions are available that are buil...
by PhilE
Thu Jul 12, 2018 2:02 pm
Forum: Device Tree
Topic: Connecting external raw nand using GPIO - RPI3b
Replies: 9
Views: 190

Re: Connecting external raw nand using GPIO - RPI3b

The exact form of a gpio declaration is system-specific. But the first term is a reference to a label in the Device Tree, where the label is meant to be attached to a GPIO controller. On Raspberry Pi devices the main user-accessible GPIOs (the ones on the 40-pin header) are provided by a DT node wit...
by PhilE
Thu Jul 12, 2018 1:33 pm
Forum: Device Tree
Topic: DT bcm watchdog - I can load it but can I start it?
Replies: 2
Views: 121

Re: DT bcm watchdog - I can load it but can I start it?

In short, no. Although the firmware is loading and manipulating the Device Tree, (with a few exceptions) only Linux is acting on it, so you are effectively asking if we can configure Linux to start the watchdog timer in case Linux doesn't load correctly. That's not as stupid as it sounds - the watch...
by PhilE
Wed Jul 11, 2018 3:41 pm
Forum: Compute Module
Topic: CM3 using DPI, I2C and SPI
Replies: 6
Views: 193

Re: CM3 using DPI, I2C and SPI

No, Device Tree isn't that hard. There are lots of example overlays in the kernel tree: https://github.com/raspberrypi/linux/tree/rpi-4.14.y/arch/arm/boot/dts/overlays There is also a utility called ovmerge (available here: https://github.com/raspberrypi/utils/blob/master/ovmerge/ovmerge) that appli...
by PhilE
Wed Jul 11, 2018 3:19 pm
Forum: Compute Module
Topic: CM3 using DPI, I2C and SPI
Replies: 6
Views: 193

Re: CM3 using DPI, I2C and SPI

You can configure your GPIO either by device tree or via overlays. I think you mean dt-blob.bin (which isn't Device Tree) or overlays (which are). To enable DPI using an overlay put one of the following lines in config.txt: dtoverlay=dpi18 dtoverlay=dpi24 But note that, as aBUGSworstnightmare says,...
by PhilE
Mon Jul 09, 2018 4:41 pm
Forum: Device Tree
Topic: RPI3 and Goodix GT9271 Touchscreen
Replies: 13
Views: 3484

Re: RPI3 and Goodix GT9271 Touchscreen

Your i2c-gpio overlay exports the symbol "i2c_gpio" for the new I2C bus, so the following ought to work:

Code: Select all

target = <&i2c_gpio>;
by PhilE
Mon Jul 09, 2018 2:55 pm
Forum: Troubleshooting
Topic: Netboot issues with mod 3 B+
Replies: 14
Views: 362

Re: Netboot issues with mod 3 B+

1. All 3B+s ship with the same SoC Boot ROM. There is no EEPROM. The only way to change the first stage loader is with a new spin of the chip, which would then be 2837C0. 2. A consequence of 1 is that if Gordon has fixed something so that booting works then that fix is available for all 3+s, not dev...
by PhilE
Mon Jul 09, 2018 1:35 pm
Forum: Device Tree
Topic: RPI3 and Goodix GT9271 Touchscreen
Replies: 13
Views: 3484

Re: RPI3 and Goodix GT9271 Touchscreen

You are running i2cdetect and finding the touchscreen on I2C bus 3, but you are declaring the touchscreen controller to be on I2C bus 0, so I wouldn't expect it to work. Which I2C bus are you actually using? On a regular Pi you should avoid i2c0 (unless it is a very early Model B) and use i2c1 inste...
by PhilE
Wed Jul 04, 2018 11:35 am
Forum: Device Tree
Topic: DT for two sc16is740 connected in the same i2c bus
Replies: 2
Views: 131

Re: DT for two sc16is740 connected in the same i2c bus

The first step is to look at the output of the "dmesg" command for errors and warnings, but my guess is that the fact that both devices are configured to use the same GPIO for interrupts may be causing a problem. You can test this hypothesis by modifying one of the instances to use a different pin -...
by PhilE
Thu Jun 28, 2018 12:19 pm
Forum: Compute Module
Topic: Something about DTS of CM3
Replies: 1
Views: 147

Re: Something about DTS of CM3

Have you seen the new "gpio" config.txt settings? It is described here: viewtopic.php?f=117&t=208748
by PhilE
Wed Jun 27, 2018 8:15 am
Forum: Compute Module
Topic: Please help to Remap pin Uart 0
Replies: 30
Views: 2557

Re: Please help to Remap pin Uart 0

Yes, I think you'll have to.
by PhilE
Tue Jun 26, 2018 2:14 pm
Forum: Compute Module
Topic: Please help to Remap pin Uart 0
Replies: 30
Views: 2557

Re: Please help to Remap pin Uart 0

Yes, dynamic Device Tree reconfiguration is not supported in all cases. I2C and SPI buses get notified of changes (because they ask), but some others don't.
by PhilE
Tue Jun 26, 2018 12:32 pm
Forum: Compute Module
Topic: cm3 network boot problem, rpiboot emmc overload problem
Replies: 11
Views: 427

Re: cm3 network boot problem, rpiboot emmc overload problem

The serial line is accessible on a CMIO via GPIOs 14 (TX) and 15 (RX) (and any GND pin).
by PhilE
Thu Jun 21, 2018 9:01 pm
Forum: Compute Module
Topic: LAN9514 chip troubleshooting
Replies: 9
Views: 534

Re: LAN9514 chip troubleshooting

From memory, does the datasheet not say that the clock has to be valid before reset is deasserted? How are you clocking the device?
by PhilE
Thu Jun 21, 2018 11:51 am
Forum: Compute Module
Topic: can a camera share an i2c bus with other devices?
Replies: 6
Views: 261

Re: can a camera share an i2c bus with other devices?

I think the answer is yes, but not in a way that would be useful to you. The SoC has two I2C busses. In theory the VPU and the ARM(s) have equal access to both, but in practice they get one each. There isn't a sharing/interlocking mechanism for guaranteeing that either side can access either bus whe...
by PhilE
Wed Jun 20, 2018 1:58 pm
Forum: Compute Module
Topic: What would be the next step up from CM3?
Replies: 29
Views: 1230

Re: What would be the next step up from CM3?

Are you seriously expecting to gather opinions about competing products on a Raspberry Pi dedicated (and funded) forum? Don't be surprised if this thread is locked or deleted.
by PhilE
Tue Jun 19, 2018 8:07 am
Forum: Device Tree
Topic: Rfid(RC522) on Raspberry pie3 is not working
Replies: 1
Views: 211

Re: Rfid(RC522) on Raspberry pie3 is not working

You almost certainly have a wiring fault somewhere - many, many people have claimed that this doesn't work, and almost all of them have been proved wrong.

Please post photos of the wiring, showing an overall view and then the details of each end so I can trace each wire through.
by PhilE
Sat Jun 16, 2018 4:19 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C failure rate
Replies: 33
Views: 5251

Re: I2C failure rate

No, clock speed being a more accurate name for the I2C bus speed set using i2c_arm_baudrate. Whatever value you find works well at idle, multiply it by 250/400 and use that add the new value.
by PhilE
Fri Jun 15, 2018 4:03 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C failure rate
Replies: 33
Views: 5251

Re: I2C failure rate

What clock speed are you requesting? My suggestion was based on the default of 100kHz, but if you have reduced this then you will also need to reduce the new value proportionally.

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