I can't detect I2C devices on PICO2 RP2350

[user-redans]

I've tried to scan i2c0 bus for any device connected with following micropython code in Thonny:

from machine import Pin, I2C
import time

i2c = I2C(0, scl=Pin(5), sda=Pin(4), freq=100000)

time.sleep(0.1)

print("Scan I2C0 (SDA=GP4, SCL=GP5)...")
devices = i2c.scan()

if devices:
    print("I2C devs detected:")
    for d in devices:
        print(" - Addr 0x{:02X}".format(d))
else:
    print("None I2C devs detected!")

I used as firmware the latest version for Cortex from official micropython download webpage, from here

Has anyone else problems with i2c0 or i2c1 initialization?

P.S. : I have to say that I did the same test on PICO1 RP2040 and it works without any problems.....

[robert-hh]

Your code works here with a PICO2 and a known good BMP085 breakout board with pull-up resistors.

[user-redans]

I did both tests (on PICO1 and PICO2 ) using a i2c CO2 sensor SCD41 and i2c bus detection script work only with Pico1, without using any resistors

**P.S. I forgot to say that I use as PICO 1 (w5500-evb-pico rp2040) and for PICO 2 (w5500-evb-pico2 rp2350)... sorry for this **

[robert-hh]

Hard to tell. Looking at the data sheets, the internal pull-up resistance is in the same range, 50-80kOhm vs. 32-86kOhm. What happens when you try a very low I2C SCL value, like 1 kHz?

[robert-hh]

So it seems that the SCL signal is missing. The signal labelled SCL looks like SDA, and a signal that should be SCL is missing.

[user-redans]

Well, you're right, sir! I've switched them labels, but I don't know why SCL is corrupt....

[robert-hh]

Did you try to use a different I2C pin pair (like GPIO 0 and 1) or a different I2C device like I2C(0)?
What happens if you use SoftI2C?

[user-redans]

Thanks for your help! I've switched to another I2C bus (I2C1 GP6 and GP7) and it works!