PiTFT: free up /dev/spidev0.1

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uhclem
 
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PiTFT: free up /dev/spidev0.1

Post by uhclem »

I have a PiTFT resistive-touch display working fine, following the Adafruit tutorial to install your custom kernel. However, I would like to use it with my FLIR Lepton module, which also needs a hardware SPI CS pin.

Looking at the PiTFT, it appears to use /dev/spidev0.0 for the display and /dev/spidev0.1 for the resistive touchscreen. I do not want the resistive touchscreen in my application. I would like to disable it.

I have tried blacklisting the stmpe_ts module in /etc/modprobe.d/raspi-blacklist.conf, but although it is not shown by 'lsmod', 'dmesg' shows it is somehow still loading:
[ 12.197534] fbtft_device: SPI devices registered:
[ 12.203803] fbtft_device: stmpe610 spi0.1 500kHz 8 bits mode=0x00
[ 12.227436] fbtft_device: fb_ili9340 spi0.0 16000kHz 8 bits mode=0x00

Can you tell me how to disable the touchscreen so I can regain /dev/spidev0.1? Thanks!

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adafruit2
 
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Re: PiTFT: free up /dev/spidev0.1

Post by adafruit2 »

ha good question! what you'll need to do is not use the adafruit pitft devices but rather use 'fbtft' as a raw device
eg try
sudo modprobe fbtft_device name=fb_ili9341
rather than adafruit28 or whatever which loads both touch and display

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uhclem
 
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Re: PiTFT: free up /dev/spidev0.1

Post by uhclem »

Doesn't seem to work:
root@flirpi:~# cat /etc/modprobe.d/adafruit.conf
options fbtft_device name=fb_ili9341 rotate=90 frequency=16000000

dmesg:
[ 11.661286] fbtft_device: display not supported: 'fb_ili9341'

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uhclem
 
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Re: PiTFT: free up /dev/spidev0.1

Post by uhclem »

aha!
sudo modprobe fbtft_device name=list; dmesg | tail -30

I see 'adafruitct28' in the list... assuming that's the capacitive touch model which I don't think uses spidev0.1.

modprobe fbtft_device name=adafruitct28 causes the console to appear on the tft
/dev/spidev0.1 is still available

This may work. I'll see shortly.

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uhclem
 
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Re: PiTFT: free up /dev/spidev0.1

Post by uhclem »

Well, the console is fine, but you can't get an image from the FLIR Lepton sensor. It could be a SPI bus timing issue; I know the lepton is particular about keeping up with it's data 'frames' (which are actually sensor scanlines).

The lepton is mounted on a board which uses the pi-style 26-conductor cable. It works fine if just plugged into the Pi, so I know there's no wiring issue. It did not work while plugged into the pitft when the pitft modules were not loaded. It might be something stupid like CE0 floating while not in use, maybe causing the pitft to interfere on the bus, but then again, when the pitft was attached and a lepton capture program was running, I was able to use the 'fbi' tool to send an image to the piftf, so who knows.

I have an old Sony PSOne LCD which takes composite and runs off 5v internally, so that's the next choice for display. Shame, the pitft looked nice.

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sashi
 
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Re: PiTFT: free up /dev/spidev0.1

Post by sashi »

The Code for the Flir lepton, is fairly easy to change what pin is used for the CS line.

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