Hello @ivanurwin the communication between PC and M5AtomS3U happens via native USB (without an external USB/Serial IC) which cannot be used with UIFlow2 UART blocks. UIFlow2 UART blocks define GPIOs for RX and TX (among others) which do not exist for a native USB connection. The only UIFlow2 block I see which will read data from the PC via a native USB connection is prompt for text with message. Thanks Felix

@ivanurwin get yourself M5Burner, log in to it with same credentials as for uiflow2, then find newest firmware for your device to burn it in to it via m5Burner