RP2040 Pico and i2c problem

[fapplin]

I'm using a DS1307 RTC board and I'm just trying to get the time.

I'm using Thonny to just do a very simple test (MicroPython v1.13-290-g556ae7914 on 2021-01-21; Raspberry Pi Pico with RP2040).

Code: Select all

from machine import I2C, Pin
i2c = I2C(1, sda=Pin(6), scl=Pin(7))
buf = i2c.readfrom_mem(0x68, 0, 7)
print(buf)

This is the error I get (which isn't very helpful). It is on the readfrom_mem() function.

Traceback (most recent call last):
File "<stdin>", line 3, in <module>
OSError: 5

I'm using

Code: Select all

https://github.com/mcauser/micropython-tinyrtc-i2c/blob/master/ds1307.py

for where I'm getting my information from.

Any ideas why I'm getting the error?

Frank

[pythoncoder]

Have you got pullup resistors on the I2C lines? Have you tried I2C.scan()?

[fapplin]

I'ĺl try it, but I've been having issues with tcs34725 sensor, too. I got an accelerometer to work, though. Is it some sensor have pull up resistors and some don't? I'm a very long time programmer but still fairly new to embedded stuff.

Thanks for the help.

[fapplin]

Dumb programmer error - I had it connected to 3.3V and not 5V. All is working!

Frank

[tannewt]

Be careful with 5v. The Pico's pins aren't 5v tolerant.

[danhalbert]

I've been having issues with tcs34725 sensor, too.

Did you get the TCS34725 to work? I've been working on the I2C support for CircuitPython. We do the same workarounds MicroPython does: short I2C writes need to be bitbang'd because the hw won't do them. Most sensors now work, but the TCS34725 still has issues. It works fine if we use software-bitbang I2C.

[DirkHartkopf]

Hi Dan,
for the TCS34725 I found the library https://github.com/adafruit/micropython ... t-tcs34725, which is depreciated, but it runs on micropython.
My small test program

import utime
from machine import Pin,I2C
import tcs34725

sda = Pin(16)
scl = Pin(17)
i2c = I2C(0,sda=sda,scl=scl,freq=400000)

sensor = tcs34725.TCS34725(i2c)
print(sensor.read())

stops at the first read statement

return self.i2c.readfrom_mem(self.address, register, 1)[0]

in function _register8 with OSError: 5
Is this error associated to the issue you mentioned?

Do you have any suitable code for the Pico to get this bitbanging running (I'm a newbie in this)
Thanks, Dirk

[danhalbert]

Do you have any suitable code for the Pico to get this bitbanging running (I'm a newbie in this)

I believe you should be able to use SoftI2C. But a MicroPython user would know more.

Code: Select all

import utime
from machine import Pin,SoftI2C
import tcs34725

sda = Pin(16)
scl = Pin(17)
i2c = SoftI2C(0,sda=sda,scl=scl,freq=400000)

sensor = tcs34725.TCS34725(i2c)
print(sensor.read())

[DirkHartkopf]

Hello Dan,
thanks for your hint, it works!

I had only to switch from I2C to SoftI2C, that's all.

Cheers Dirk