Unable to get UART to receive

ESPHome
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1

Hey,

I’m really struggeling to get my esphome to receive something over UART.

I bought a IR-Read-Head to connect to my smart meter (hardware:controllers:ir-schreib-lesekopf-ttl-ausgang [wiki.volkszaehler.org]).

It’s wired correctly to the RX-Pin of my Wemos D1 Mini, but I’m unable to see at least a byte being received via uart.

What did I try?

  • The smart meter sends IR data (verified with phone camera)
  • With my multimeter I could see the voltage on the RX Pin drop from 3.3V slightly every second (the sending interval of the smart meter)
  • I double checked the communication settings (9600 Baud, 7E1) with the specification of the smart meter
  • I tried all combinations of INPUT_PULLUP, INPUT, inverted for the pin
  • I activated software uart - was hoping to see more debug output. But it doesn’t show any.
  • Instead of the UART platform, i tried the remote_receiver, which logged me tons of received signals, so something seems to be received via infrared - just not ending in UART.

This is my config right now:

esphome:
  name: "stromzaehler"

esp8266:
  board: esp01_1m

[...]

uart:
  id: uart_bus
  baud_rate: 9600
  rx_pin: 
    number: GPIO03
  data_bits: 7
  parity: EVEN
  stop_bits: 1
  debug:
    after:
      timeout: 100ms

I have no idea how to debug this further… is there a way to get more debug-information about what’s going on inside the uart (maybe checksum mismatch, wrong baudrate, whatever)…

Anyone an idea how to debug this further?

Thanks, David

2

Start with hardware, then protocol, then software.

One question - does the sensor really output RS232 data at a known rate (e.g. 96008N1), or is the UART really just a GPIO used to bit-bang read an arbitrary protocol (similar to remote control IR codes)?

  • Connect the sensor head to something else - e.g. a USB FTDI serial board set to 3V3.

  • Reverse Tx / Rx

  • Change bps speed - do you get anything? Even noise should generate rubbish.

  • Link Tx to Rx to check your terminal emulator

  • Is the signal inverted? (mark-space would be wrong)

  • Try a sound card as a crap oscilloscope?

  • Use the FTDI board to send known serial to ESPhome

3

The “sound card as oscillosope” tip was great… i tried it and saw that my settings are right.

I solved the problem, it was actually just a stupid error on my side. For UART Input to be logged, the dummy_receiver in esphome needs to be enabled. I did it and now everything works fine.