Programming the Coin Acceptor
=============================

The ATM uses a programmable **HX-616** pulse coin acceptor. It must be taught
which coins to accept and how many pulses to emit for each, before it is wired to
the ESP32.

.. warning::

   Adjust the output voltage of the step-up converter **before** connecting the
   coin acceptor — it runs on **12 V**. Powering it incorrectly can damage the
   unit.

How pulse counting works
------------------------

The coin acceptor signals each recognised coin by emitting a number of pulses on
its "Coin" line (wired to GPIO 17 — see :doc:`wiring`). The firmware counts those
pulses with a debounced interrupt and maps the pulse count to a cent value. When
you program the acceptor, assign each coin a distinct pulse count so the firmware
can tell them apart.

Programming guides
------------------

Follow one of these detailed guides to program the acceptor for your coins:

- `Coin Acceptor Programming Guide (English)
  <https://github.com/21isenough/LightningATM/blob/master/docs/guide/coin_validator.md>`_
- `Coin Acceptor Programming Guide (German)
  <https://ereignishorizont.xyz/lightning-atm/>`_

Once programmed, wire the acceptor and its blocking MOSFET as described in
:doc:`wiring`.