Money acceptors (pulse)

pulseacceptor repository contains a library and a daemon for coin acceptors and bill acceptors that use the pulse interface.

pulseacceptor.go contains a small library for counting pulses from a GPIO pin. The input is denoised and debounced.
cmd/pulse-watcher contains a program for checking the pulse and pause widths sent by the device.
cmd/pulseacceptord is a daemon that counts pulses, translates them into monetary values and sends this information to Redis.

pulse-watcher is an useful program that prints widths of each pulse and pause. Upon exiting it also prints averages for both. You can use it to figure out values for debounce and denoise parameters for pulseacceptord.

Install by running:

go install gitlab.com/openkiosk/pulseacceptor/cmd/pulse-watcher@latest

Example usage:

# Listen on GPIO pin 17 for pulses, if no pulses follow after 101 milliseconds
# ignore this pause because pulses for this bill/coin has ended.
pulse-watcher -pin 17 -timeout 101ms

pulseacceptord denoises and debounces the pulses to prevent noise. After it is done counting pulses for a single bill/coin, it sends the event in to MQTT for queueing.

Install by running:

go install gitlab.com/openkiosk/pulseacceptor/cmd/pulseacceptord@latest

Change the values inside config.yaml before running.

denoise: Should be set to the pulse width. Although you might want to add or deduct a very little amount from this value to allow for some error. Pulse widths smaller than this value will be ignored.

debounce: Should be set to the pause width. Again, tune this value for possible errors like you should do for the denoise parameter. After a valid pulse (with width longer than the denoise parameter) has been received, more pulses will be ignored for the debounce amount. Meaning repeated pulses within debounce duration are ignored.

config.yaml:

device:
  pulse_pin: 17
  # Some devices write an extra low/high when beginning to send pulses
  # You might need this mode if you notice that always 1 pulse is missing
  plus_one_mode: true
  debounce: "110ms"
  denoise: "29ms"

# Some devices have "enable" pins to start/stop money input.
enable_pin_control: true
# Specify if enable_pin_control is enabled.
enable_pin: 27
# Is it enabled when the signal is high?
enabled_when_high: false

# pulses: amount
values:
  2: 10
  4: 20
  10: 50
  20: 100
  40: 200

mqtt:
  brokers:
    - "mqtt://127.0.0.1:1883"
  topic: "pulseacceptord"
  client_id: "pulseacceptord-1"

pin is the GPIO input pin that is connected to the COIN pin. The values map is for translating pulses to monetary values. In the above configuration file if your device were to send 2 pulses, coinacceptord would send an event with "value": 10 to the backend.