MAX7219 7-segment display in reverse order

ESPHome
1

Hi Forum,
I have a custom display with 7-segment displays based on an ESP-01 and 4 MAX7219. Up until now I have used it with custom Arduino code but I would like to use it with ESPHome. My problem is that apparently the commercially available displays are wired high to low, so digit 7 is the first and digit 0 the last. My custom display is wired low to high though so any values sent to the display are in reverse. I send 01234567 and get 76543210 on the display.

Is there an easy way to solve this in ESPHome? The reverse_enable option only reverses the order of the MAX7219 ICs in the daisychain, not the digits themself.

I would love to use my display with this to show values from HomeAssistant but right now it is obviously quite useless.

2

Hi @qetesh, just wondering if you ever found a solution to this problem. I have a 3-digit 7-segment display with MAX7219 and have the same issue. I need to reverse the string sent to each display but can figure out how to do it. Something to the effect of this, but that compiles:

display:
  - platform: max7219
    cs_pin: GPIO1
    num_chips: 3
    reverse_enable: True
    update_interval: 5s
    lambda: |-
      char buftm[10];
      sprintf(buftm, "%.1f", id(tm1).state);
      it.printf(7, "%.1f", strrev(buftm));

Thanks

3

Unfortunately not. But I also didnt try any further and just updated my arduino code.