I have successfully received the current time and the divisor. And also send data to the Node-RED server. The code is pushed to GitHub.
For now I have some troubles with the MicroPython code, but I am not sure where to locate the problem. Sometimes the code gets stuck and the ampy tool shows a timeout.
When this problem is fixed, I will start a long-time test run without deep-sleep (M5StickC plugged to a power supply).