<![CDATA[unable to connect to CO2L unit]]>Hi,

I am new to M5Stack and started to play with small things to learn. After playing with basic UI controls (which works great), I wanted to use some external sensor and connected my CO2L unit to port A.

My current setup is thus made of a CORE2 connected to a CO2L unit, and I am using uiflow.

0_1692889775167_Screenshot_20230824_170417.png

I reduced the test progam to the bare minimum: I declared the CO2L unit and left everything else empty. This results in the following micropython code:

from m5stack import *
from m5stack_ui import *
from uiflow import *
import unit


screen = M5Screen()
screen.clean_screen()
screen.set_screen_bg_color(0xFFFFFF)
co2l_1 = unit.get(unit.CO2_SCD41, unit.PORTA)

So, I am stuck with a "CO2 unit maybe not connect" error message as if nothing was connected. Am I doing something wrong, or is the sensor faulty (I just received it)?
Is there any way to debug?

Thanks!

]]>https://community.m5stack.com/topic/5606/unable-to-connect-to-co2l-unitRSS for NodeWed, 29 Apr 2026 04:47:31 GMTThu, 24 Aug 2023 15:15:32 GMT60<![CDATA[Reply to unable to connect to CO2L unit on Thu, 14 Dec 2023 16:31:35 GMT]]>To close this topic: I have no problem with a newly ordered sensor. I was apparently unlucky enough that my first sensor was faulty.

]]>https://community.m5stack.com/post/23044https://community.m5stack.com/post/23044Thu, 14 Dec 2023 16:31:35 GMT<![CDATA[Reply to unable to connect to CO2L unit on Fri, 25 Aug 2023 13:13:22 GMT]]>I managed to get the Arduino UI running with the CORE2 (using the M5Unified 0.1.9 and the Sensirion I2C SCD4X 0.4.4 libraries).

I took the example ino file and modified the header to use M5Unified.h instead of M5stack.h... and the problem seems to be there as well.

The first call to scd4x.stopPeriodicMeasurement() returns an error saying: Error writing to I2C bus. Then it hangs apparently on the subsequent scd4x.startPeriodicMeasurement() call, for what I can say.

]]>https://community.m5stack.com/post/22068https://community.m5stack.com/post/22068Fri, 25 Aug 2023 13:13:22 GMT<![CDATA[Reply to unable to connect to CO2L unit on Fri, 25 Aug 2023 09:13:24 GMT]]>Thanks for checking!
I will be happy to make any additional test with my unit. It may be worth noting that on my first attempt (reproducing the example with default fonts just as @mtylerjr) I got the serial number (and nothing else) but that it was not reproducible: I got the error immediately after that first attempt.

I can try to look with arduino UI, but I have no experience there, so it is likely to take some time.

In the meanwhile, I repeated the test with an ATOM Lite for the same result.

P.S.: I tried accessing the UNIT with bare I2C without success, but I have no working example to confirm that I am using the I2C blocks properly.

]]>https://community.m5stack.com/post/22064https://community.m5stack.com/post/22064Fri, 25 Aug 2023 09:13:24 GMT<![CDATA[Reply to unable to connect to CO2L unit on Fri, 25 Aug 2023 09:00:41 GMT]]>@mtylerjr Just tested the M5 demo example with my CO2 unit.. I don't have the L version, actually was not aware of its existence.
After a first run the sketch reported errors, the demo program uses Ubuntu font that does not exist on Core 2 UIFlow 1.12.3... I replaced all the labels fonts by default and yes the sensor works on Core 20_1692954046604_CO2sensor.jpg

]]>https://community.m5stack.com/post/22063https://community.m5stack.com/post/22063Fri, 25 Aug 2023 09:00:41 GMT<![CDATA[Reply to unable to connect to CO2L unit on Fri, 25 Aug 2023 04:14:28 GMT]]>@mtylerjr It likely works in Arduino IDE.

]]>https://community.m5stack.com/post/22057https://community.m5stack.com/post/22057Fri, 25 Aug 2023 04:14:28 GMT<![CDATA[Reply to unable to connect to CO2L unit on Fri, 25 Aug 2023 00:13:38 GMT]]>I am placing another order tomorrow, and this is one of the units I was intending to add.

Does the slightly less pro version of this (the non-L version) have the same issue? Anyone know?

(and I realize the issue is almost certainly in the interface/UIFlow/libraries and not the unit itself)

]]>https://community.m5stack.com/post/22056https://community.m5stack.com/post/22056Fri, 25 Aug 2023 00:13:38 GMT<![CDATA[Reply to unable to connect to CO2L unit on Thu, 24 Aug 2023 17:49:43 GMT]]>I just checked and yes I agree that there is an issue with UIFlow.

]]>https://community.m5stack.com/post/22053https://community.m5stack.com/post/22053Thu, 24 Aug 2023 17:49:43 GMT<![CDATA[Reply to unable to connect to CO2L unit on Thu, 24 Aug 2023 16:05:19 GMT]]>I think so: I installed the v1.12.3

]]>https://community.m5stack.com/post/22052https://community.m5stack.com/post/22052Thu, 24 Aug 2023 16:05:19 GMT<![CDATA[Reply to unable to connect to CO2L unit on Thu, 24 Aug 2023 16:03:10 GMT]]>@m5stack I'm getting error 19 with latest UIFLow (1) firmware.

]]>https://community.m5stack.com/post/22051https://community.m5stack.com/post/22051Thu, 24 Aug 2023 16:03:10 GMT<![CDATA[Reply to unable to connect to CO2L unit on Thu, 24 Aug 2023 15:58:33 GMT]]>Have you updated to the Latest firmware for the Core2?

]]>https://community.m5stack.com/post/22050https://community.m5stack.com/post/22050Thu, 24 Aug 2023 15:58:33 GMT