Hopefully I can shed a little light on this topic. The AIN4-20mA unit uses a STM32 processor to handle the I2C interface in software. For some reason, the timing is not wholly compatible with the Raspberry Pi kernel I2C drivers. However, the Espressif I2C implementation is a lot more tolerant and flexible and works just fine. That's why it works with the M5 controllers. There was a an update to the github repo for this unit's firmware (https://github.com/m5stack/M5Module-4-20mA-Internal-FW) which changed the I2C library that was used. It's possible that this will fix it, but I haven't bothered to set up a STM32 development system to try it. If you really want to use a Pi or other Linux host board, you could use any inexpensive ESP device (like an M5Stamp) as a go-between. Another option is to use something like the Arduino UNO Q, which runs Linux on the main processor and allows you to run C++ code on the STM32 microcontroller to talk to I2C devices. It's really better to run real-time control on a separate microcontroller anyway.

In case anyone else comes across this post, it appears that the wires coming out of the DinMeter PortB are reversed to the label, at least on my unit. G1 is the yellow wire, and G2 is the white one. It works as expected to do a digital read on the pins for a button push.

@kuriko Thanks. How can I do it?

Thanks. How can I do it?

@HappyUser Found it in the Meshtastic app on OSX under device settings. Btw, IOS app does not allow for tcp connections as it seems.

On the cores3 (module connected through port A), I see no devices found on i2c scan when using esphome. It finds OK on the atom-lite. If using the "Cores3 test" binary from m5stack, I can see the address found on the i2c scan app.

Hello @HappyUser just curious, which SIM module did you settle on? Thanks Felix

Hello @MitchBuckanon like @robski mentioned, M5Dial has two ports: A and B which gives you 4 GPIOs you can use. In my test I configured the GPIOs like below: #define ETH_PHY_CS 1 #define ETH_PHY_IRQ -1 #define ETH_PHY_RST -1 #define ETH_SPI_SCK 13 #define ETH_SPI_MISO 15 #define ETH_SPI_MOSI 2 Below is how I wired M5Dial to the LAN module (using a Bus Module) and some Grove/Dupont cables. [image: 1772456287475-m5dial_to_lan_via_bus_module_20260302.png] Hope this helps. Thanks Felix

@felmue said in M5Unit C6L Lora initialisation error: here thank you for figuring that out. Honestly, i would have expected that that would be dealt with in M5Unified. Anyway, module works great. Cam right on time on the market because we really need to upgrade our iot devices in the field.

@felmue Thank you for the clarification. Yes, it seems that internal pull-up/pull-down resistors cannot be controlled at the moment. I also checked the documentation, but could not find any way to configure this, which is why I posted the question here. I hope this feature can be supported in the future, as it would be very useful in practice. Thanks again for sharing your experience.

Hello @Mamoulian thank you for that information. I was not aware the the timers in ESP32S3 are also called RTC timers. Thanks Felix

I'm trying to upload a new firmware on the unit roller connecting a ST_Link v2 to the SPI connector with STM32CubeProgrammer. Roller SPI ---------------- ST_LinkV2 V --------------------- 3.3 G -------------------- GND C ------------------ SWCLOCK D ------------------ SWDIO O ------------------- NC when the firmware si uploaded the unit roller works (display right boot image and information, led is on, button and encoder works and menu works too), but if I disconnect the SPI cable and I power the unit from grove or dc in 6/16v, the unit doesn't work(black display, led off, etc). this is the .hex firmware used. and this is the cube log: 22:11:59 : MASS ERASE ... 22:11:59 : Mass erase successfully achieved 22:11:59 : UPLOADING ... 22:11:59 : Size : 1024 Bytes 22:11:59 : Address : 0x8000000 22:11:59 : Read progress: 22:11:59 : Data read successfully 22:11:59 : Time elapsed during the read operation is: 00:00:00.019 22:12:36 : Opening and parsing file: ROLLERCAN.hex 22:12:36 : Memory Programming ... 22:12:36 : File : ROLLERCAN.hex 22:12:36 : Size : 94.38 KB 22:12:36 : Address : 0x08002000 22:12:36 : Erasing memory corresponding to segment 0: 22:12:36 : Erasing internal memory sectors [4 51] 22:12:37 : Download in Progress: 22:12:39 : File download complete 22:12:39 : Time elapsed during download operation: 00:00:02.735 22:12:39 : Verifying... 22:12:39 : Read progress: 22:12:39 : Time elapsed during verifying operation: 00:00:00.645 22:12:39 : Download verified successfully 22:12:39 : Memory [0x08000000 : 0x08020000] - Checksum : 0x011ED0C0 22:12:39 : RUNNING Program ... 22:12:39 : Address: : 0x08002000 22:12:39 : Application is running, Please Hold on... 22:12:39 : Start operation achieved successfully this is the log of OB: { "deviceId" : 1128, "bitNameToValue" : { "RDP" : 170, "BOR_LEV" : 0, "nRST_STOP" : 1, "nRST_STDBY" : 1, "nRST_SHDW" : 1, "IWDG_SW" : 1, "IWDG_STOP" : 1, "IWDG_STDBY" : 1, "WWDG_SW" : 1, "nBOOT1" : 1, "SRAM_PE" : 1, "CCMSRAM_RST" : 1, "nSWBOOT0" : 1, "nBOOT0" : 1, "NRST_MODE" : 3, "IRHEN" : 1, "PCROP1_STRT" : 16383, "PCROP1_END" : 0, "PCROP_RDP" : 0, "WRP1A_STRT" : 63, "WRP1A_END" : 0, "WRP1B_STRT" : 63, "WRP1B_END" : 0, "SEC_SIZE1" : 0, "BOOT_LOCK" : 0 } } If I power the unit from grove or DC in, I have 3.3v on SPI (V,G). I tried to merge and burn a bootloader.hex too but no joy. after uploading the firmware if I connect the grove cable of an atom lite running a i2c scanner code, I can see 0x64 on serial monitor. I can also disconnect the SPI cable and the roller still works until a power cycle. ideas?? tnks a lot!!

@maiknaef Hello. I have same problem with AtomS3, nanoC6 and Atom lite and Din Meter. However M5dial works fine. I tested Uiflow2.4.0 and 2.4.1. It is strange because M5dial and M5Din meter are uses StampS3. Sorry I have no idea at this moment, however hopefully it solved in future.

from M5Docs: ENV Pro Unit is an environmental sensor that utilizes the BME688 sensor solution, supporting the measurement of various environmental parameters such as volatile organic compounds (VOCs), indoor air quality (IAQ), temperature, humidity, and atmospheric pressure. [image: 1762932826623-env-pro.jpg]