Thank you Felix, I solved my problem, it was clearly an internal pullup detail: esp_sleep_enable_ext0_wakeup(GPIO_NUM_37,0);//Configure GPIO37 as ext0 wake up source for low logic level gpio_pullup_en(GPIO_NUM_37);

@felmue Thanks Felix for the reply. I wired the pin 27 for RX and now both RS-485 and I2C works fine. Regards

Hi ajb2k3, Thanks for taking time out to reply to my post. I guess the question I should have asked is how do I make use of it in UI Flow? Do I not need to add it in as a unit? And if not, then is the block I use the first option in Functions? I've viewed the YouTube videos but an example of UI Flow with external connections would be good for the beginners. For example, connecting an LED/resistor that lights when a button is pressed would be good. Cheers, Syd *** Update. I've just found a YouTube large video library. Hoping to find something in there.

I made custom block for uiflow for do this. But i implemented use only one sensor per gpio pin without checking crc errors (shorter and simplicity code). https://github.com/stonatm/UiFlow-custom-blocks/tree/master/ds18b20 and here is python code used in this custom block: https://github.com/stonatm/M5Atom_matrix_library/blob/master/lib/dallas.py Try connect sensor to SDA pin in groove port, but you must find a number of gpio pin assigned for this line. You also should connect a pullup resistor (2-10kohm) betwen sensor DQ pin and sensor Vcc. In my case i use ds18b20 without this resistor, but my connection to sensor is shorter than 10cm.

No can do I am afraid. The atoms don't have native built in usb.