I2c0 vs i2c1 on VIM2

VIM2
1

I have a display I can connect to using GPIO pins 25/26 (i2c1) but I cannot use i2c0 pins 22/23 to connect to the same display. I’m on the latest Ubuntu V1.0.5-210430 on VIM2. Help please?

/boot/env.txt

Screenshot 2021-06-22 at 17.58.16
Screenshot 2021-06-22 at 17.58.161130×288 68.5 KB

gpio readall

Screenshot 2021-06-22 at 17.51.09
Screenshot 2021-06-22 at 17.51.091548×672 209 KB

I noticed that pins 22/23 are not configured for ALT4(?) - which the working i2c(i2c1) bus is? I tried a gpio mode 22 ALTx but got a warn : (pinModeAlt):THis function is not supported by KHADAS Board..

I want to access I2C0 because it is passed through the Tone board and into the OLED FPC connector. Has anyone successfully managed to use this bus?

dmseg:

sudo dmesg | grep i2c
[    1.375747] i2c /dev entries driver
[    2.303491] meson-gxl-pinctrl pinctrl@4b0: pin GPIODV_24 already requested by c1108500.i2c; cannot claim for d0042000.snd_dmic
2

Yes, but I2C0 works.

root@Khadas:~# i2cdetect -l
i2c-1	i2c       	Meson I2C adapter               	I2C adapter
i2c-0	i2c       	Meson I2C adapter               	I2C adapter
root@Khadas:~# i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- 39 -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

The devide 0x39 on I2C0 detected.

1 Like
3

Thanks for fast reply, but I2C0 is not behaving like I2C1 does. I’m not sure what I’m missing?

Connected via I2C1 - can draw pixels:

IMG_0848.HEIC
IMG_0848.HEIC3024×4032 2.37 MB

Connected via I2C0 - can’t connect:

IMG_0844.HEIC
IMG_0844.HEIC3024×4032 2.6 MB

Attempting to connect to the I2C0 bus generates this error via python:
IOError: [Errno 6] No such device or address

Where as the same code targeting I2C1 works. As per image.

from smbus import SMBus
import time

def main():
    '''
    Main program function
    '''
    # Define registers values from datasheet
    i2cbus = SMBus(0)  # Create a new I2C bus
    i2caddress = 0x70  # Address of device

    i2cbus.write_byte(i2caddress, 0x1B) 
    i2cbus.write_byte(i2caddress, 0x4A)  
    i2cbus.write_byte(i2caddress, 0x43)  
    i2cbus.write_byte(i2caddress, 0x44)  
    
    i2cbus.write_byte(i2caddress, 0x1B)  
    i2cbus.write_byte(i2caddress, 0x4A)  
    i2cbus.write_byte(i2caddress, 0x30)  
    
    i2cbus.write_byte(i2caddress, 0x0000) 
    i2cbus.write_byte(i2caddress, 0x0000>>8)  

    i2cbus.write_byte(i2caddress, 0x31) 
    
    i2cbus.write_byte(i2caddress, 0x0008)  
    i2cbus.write_byte(i2caddress, 0x0008>>8)  
    
    i2cbus.write_byte(i2caddress, 0xFF)  
    i2cbus.write_byte(i2caddress, 0x00)  
    i2cbus.write_byte(i2caddress, 0xFF)  
    i2cbus.write_byte(i2caddress, 0xFF)  
    i2cbus.write_byte(i2caddress, 0xFF)  
    i2cbus.write_byte(i2caddress, 0xFF)  
    i2cbus.write_byte(i2caddress, 0xFF)  
if __name__ == "__main__":
    main()

Strange huh? I’m pretty baffled.

For reference I have a more elaborate piece of code in Rust - which also works via I2C1, but not 0. So I presume it’s a something outside of the language.

4

Any assistance here?

We’ve enjoyed working on the VIM for this prototype, but if it’s not stable for development we’ll move onto another supplier for our production run.

5

OK, I will use your code check on my side.

1 Like
6

Thank you, much appreciated.

I’ve either missed something very obvious or it’s beyond my skill set.

7

It seems no i2c0 node. Can you check the i2c node ?

$ i2cdetect -l
$ i2cdetect -y 0
8

I tested a I2C device APDS9960 on my hand on I2C0, it works well.

Test image: https://dl.khadas.com/Firmware/VIM2/Ubuntu/EMMC/VIM2_Ubuntu-server-bionic_Linux-4.9_arm64_EMMC_V1.0.5-210430.img.xz

Just flash, without any modifications.

khadas@Khadas:~/apds9960_demo$ uname -a
Linux Khadas 4.9.241 #10 SMP PREEMPT Fri Apr 30 16:23:48 CST 2021 aarch64 aarch64 aarch64 GNU/Linux
khadas@Khadas:~/apds9960_demo$ 
khadas@Khadas:~/apds9960_demo$ cat /etc/fenix-release 
# PLEASE DO NOT EDIT THIS FILE
BOARD=VIM2
VENDOR=Amlogic
VERSION=1.0.5
ARCH=arm64
INITRD_ARCH=arm64
INSTALL_TYPE=EMMC
IMAGE_VERSION=V1.0.5-210430
################ GIT VERSION ################
UBOOT_GIT_VERSION=khadas-vims-v1.0.5-release
LINUX_GIT_VERSION=khadas-vims-v1.0.5-release
FENIX_GIT_VERSION=v1.0.5
#############################################

Test code:

khadas@Khadas:~/apds9960_demo$ cat test_prox.py 
from apds9960.const import *
from apds9960 import APDS9960
import smbus
from time import sleep

port = 0
bus = smbus.SMBus(port)

apds = APDS9960(bus)

def intH(channel):
    print("INTERRUPT")

try:
    apds.setProximityIntLowThreshold(50)

    print("Proximity Sensor Test")
    print("=====================")
    apds.enableProximitySensor()
    oval = -1
    while True:
        sleep(0.25)
        val = apds.readProximity()
        if val != oval:
            print("proximity={}".format(val))
            oval = val

finally:
    print "Bye"

Test result:

khadas@Khadas:~/apds9960_demo$ python test_prox.py
Proximity Sensor Test
=====================
proximity=142
proximity=141
proximity=142
proximity=143
proximity=142
proximity=143
proximity=141
proximity=142
proximity=141
proximity=142
proximity=139
proximity=141
proximity=143
proximity=153
proximity=150
proximity=147
proximity=255
proximity=114
proximity=127
proximity=245
proximity=255
proximity=137
proximity=134
proximity=138
proximity=137
proximity=138
proximity=143
proximity=255
proximity=134
proximity=137
proximity=135
proximity=136
proximity=134
9

Appreciate the assistance, but I’m going to pause the project here.

Here’s my notes for anyone coming across the same issues:

https://dl.khadas.com/Firmware/VIM2/Ubuntu/EMMC/VIM2_Ubuntu-server-bionic_Linux-4.9_arm64_EMMC_V1.0.5-210430.img.xz isn’t accepted as a viable image when placed into /dumps/ for krescue. I used https://dl.khadas.com/Firmware/VIM2/Ubuntu/SD_USB/VIM2_Ubuntu-server-bionic_Linux-4.9_arm64_SD-USB_V1.0.5-210430.img.xz but this did not recognise the Tone1 board or IC20.

• Ubuntu 4.9 allows access to I2C-1 but did not recognise a Tone board
• Ubuntu 5.12/5.7 recognises Tone board, but does not recognise I2C buses
• In no circumstance was I able to communicate via I2C0 on a VIM2
• FPC I2C on Tone1/VIM2 GPIO passthrough supplies current but no data
• GPIO settings change between Ubuntu versions (I2C1 becoming In/Out vs Alt2) etc

It’s entirely possible I fried a part of the board and this is an anomaly :woman_shrugging: