Issue with shift registers for LEDs

[gabooboo]

Hello,

Huge fan of this project!

I'm having an issue with getting single color LEDs to light up using the SparkFun Shift Register Breakout - 74HC595 (https://www.sparkfun.com/products/10680). I believe this is a supported shift register but I could be wrong.

I am using a custom board variant on an Arduino Mega 2560. Here is the LED section of my YAML file:

leds:
  external:
    type: "shiftRegister"
    shiftRegisters: 2
    pins:
      data:
        port: "H"
        index: 0
      clock:
        port: "J"
        index: 0
      latch:
        port: "H"
        index: 1
      enable:
        port: "J"
        index: 1

I've also attached an image of the breakout board and of my shift register circuit.

For the shift register breakout board, I have the "data" pin to "SER_IN", "clock" to "CLOCK", "latch" to "L_CLOCK" and "enable" to "/OE".

However, I can't get any LEDs to turn on when I try testing them in the web configurator.

Any idea what might be wrong or how I can further debug the issue? If you need more info from me, I'd be happy to provide it.

Thanks in advance!

[paradajz]

You need to set shiftRegisters to 1 if you're using only 1

[gabooboo]

Thank you for the fast response!

My mistake. I actually do have 2 shift registers connected. I just got lazy with my initial circuit diagram :(

Here is the correct circuit showing the 2 shift register breakout boards connected in series:

[paradajz]

Can you send me your entire yml file?

[gabooboo]

Yes, here it is.

Using the mega2560_muxsh2.yml as an example, I added a section for unused-io even though there was no documentation for it.

---
  arch: "avr"
  mcuFamily: "avr8"
  mcu: "atmega2560"
  usb: false
  dinMIDI:
    uartChannel: 1
  display:
    i2cChannel: 0
  touchscreen:
    uartChannel: 1
    components: 32
  buttons:
    type: "native"
    pins:
    -
      port: "B"
      index: 1
    -
      port: "B"
      index: 3
  analog:
    type: "4067"
    multiplexers: 2
    pins:
      s0:
        port: "E"
        index: 4
      s1:
        port: "G"
        index: 5
      s2:
        port: "H"
        index: 3
      s3:
        port: "H"
        index: 4
      z0:
        port: "F"
        index: 0
      z1:
        port: "F"
        index: 1
  leds:
    external:
      type: "shiftRegister"
      shiftRegisters: 2
      pins:
        data:
          port: "H"
          index: 0
        clock:
          port: "J"
          index: 0
        latch:
          port: "H"
          index: 1
        enable:
          port: "J"
          index: 1
  unused-io:
  -
    port: "A"
    index: 1
    state: "high"
  -
    port: "A"
    index: 3
    state: "high"
  -
    port: "A"
    index: 5
    state: "high"
  usbLink:
    type: "slave"
    uartChannel: 0
  bootloader:
    button:
      port: "B"
      index: 2

[paradajz]

You need to connect pin 10 from shift register to Vcc (reset)

[gabooboo]

This was the answer for me. I can now get all my LEDs to turn on.

Thank you! And again, amazing work on the project!

[paradajz]

Glad you like it! I'll mention the reset pin in wiki.

[gabooboo]

Ok, thank you. Ill try connecting "/RESET" on the breakout boards to Vcc and report back.

I also got another response from you that I don't see here anymore:

unused-io is undocumented since I need to rework it a bit. Probably in the coming days. I now see that you have connected shift register pins to pins used by DIN MIDI/touchscreen. TX2/RX2 is the UART channel I use for those things and you have that enabled in your config. So either try removing DIN MIDI and touchscreen from your config or use different pins for shift register.

Do you still see a conflict with the pins? Changing the pins is not a problem for me. Will any unused pins do?

[paradajz]

I've written that too hastily - I actually use TX1/RX1 - figured that after I've written that. No need to change the pins in the config.