Hi there,
I’m trying to connect a Pn532 RFID reader via the i2c “break out” connector of the HyperPixel 2" round. But no luck so far. There is simply no i2c-3
sudo i2cdetect -y 3
Error: Could not open file `/dev/i2c-3' or `/dev/i2c/3': No such file or directory
There is “funny” thing though, I can symlink i2c-7 instead of i2c-3, but it looks like it’s used by both the HyperPixel and the device on the breakout:
$ sudo i2cdetect -y 7
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- 15 -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- 24 -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
Now I can talk to the Pn532, but the display is creating “funny” colours (see attached photo)… So apparently they shouldn’t sit on the same i2c device.
Am I missing something?? Do I need to connect the ‘Int’ pin or something? I connected GND, 3V3, SCL, SDA, and as I said, that works technically, but the screen gets confused.
Edit: Also I notice the symlink is gone when I reboot; is this normal? Does it have to be recreated after every boot? Is there an additional step missing that “activates” i2c-3 somehow? All I did to make the hyperpixel work is run the install.sh script. Perhaps the additional i2c must be activated?
Edit: for the record, here is my /boot/config.txt:
# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
disable_overscan=1
# uncomment to force a console size. By default it will be display's size minus
# overscan.
framebuffer_width=480 # 1280
framebuffer_height=480 # 720
# uncomment if hdmi display is not detected and composite is being output
hdmi_force_hotplug=1
# Uncomment some or all of these to enable the optional hardware interfaces
dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on
# Additional overlays and parameters are documented /boot/overlays/README
# Enable audio (loads snd_bcm2835)
dtparam=audio=off
[pi4]
# Enable DRM VC4 V3D driver on top of the dispmanx display stack
dtoverlay=vc4-fkms-v3d
max_framebuffers=2
[all]
#dtoverlay=vc4-fkms-v3d
dtoverlay=hyperpixel2r
enable_dpi_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x7f216
dpi_timings=480 0 10 16 55 480 0 15 60 15 0 0 0 60 0 19200000 6
# TEST
#dtparam=i2c3=on
#dtoverlay=i2c-gpio,i2c_gpio_sda=10,i2c_gpio_scl=11
You can see I tried the TEST bit, following some hunches here but that only freezes the Pi at boot time, so doesn’t work.
