What is in the box

Two things you will wire and four you will put in a drawer. The part worth memorising is the module's two headers, because they are in different orders and everybody wires one of them by counting across from the other.

Updated 2026-09-133 min readcoin acceptor

What is in it

The kit laid out: the small square black module board with a USB-C socket and a four-pin header down each edge, the much larger black coin acceptor with its coin slot and reject flap, a gold-coloured token, four long machine screws, four nuts, and a four-way wiring harness with a white plug on one end. — The module is the postage-stamp board on the left. Everything to the right of the acceptor is mounting hardware, the harness, and a token for testing.

The acceptor and the module are the two things you wire. The screws and nuts are for bolting the acceptor into a panel — it is designed to be let into the front of a cabinet. The harness joins the acceptor to the module, and the token is for checking the mechanism turns over.

There is a printed quick-start guide in the box as well, and it is the same document as the one in the library's repository.

The module, pin by pin

The board is a square with a USB-C socket on one edge and a four-pin header down each side. The silkscreen names both: COIN ACCEPTOR on one, MCU on the other.

Two headers, and they are not mirror images

COIN ACCEPTOR side · 12V

Which header

Which pin

12V — the red wire. The 12 V the acceptor runs on. This is the only 12 V on the board and it is made here, not brought in. Never wire it to a microcontroller.

The two rows are not mirror images of each other, and that is the single most useful thing on this page. Count across the board from 12V and you land on GND. Count across from GND and you land on COIN. Read the silkscreen for each wire instead.

The coin acceptor module seen straight down: black board, white silkscreen, a USB-C socket centred on the top edge, a shielded inductor and a small chip in the middle, the header on the left labelled COIN ACCEPTOR with pins 12V, COIN, GND and COUNTER, the header on the right labelled MCU with pins GND, VCC, COIN and COUNTER, four mounting holes, and lonely binary printed along the bottom. — The metal cube in the middle is the boost converter's inductor — it is what makes 12 V out of the USB-C 5 V. The four-pin rows read top to bottom in the order printed beside them.

The acceptor

The coin acceptor at an angle: a black plastic body about the size of a paperback behind a flat front plate with a vertical coin slot, a hinged reject lever below it, four bolt holes at the corners of the plate, and on the side a two-digit red display, three round buttons and a row of small switches. — The front plate bolts into a panel; the body hangs behind it. Everything you configure is on the side you cannot see once it is mounted, which is a good reason to set it up first.

On the side there is a two-digit display, three buttons — +, − and SET — and a row of small switches. The display and the buttons are how you tell it which coins to accept; the switches set how it reports them. Both are covered in the two switches and the two pages after it.

Out of the box the acceptor knows no coins at all. It will reject everything, including the token, until it has been trained.

When it does not work

The header pins are not soldered on, or not in the holes I want

The module ships with headers fitted, in the photograph and in ours. If yours arrived with loose strips instead, solder them into the two four-pin rows — the silkscreen names every pin on the top side, so fit them from the top and solder underneath.

There is a gold-coloured coin in the box. Is it currency?

It is a token, for checking that the mechanism runs before you have trained it on anything. Do not train a coin type on it unless you actually want the machine to accept tokens — you would be spending one of your six coin types on it.

I counted the pins across from each other and nothing works

That is the trap. The acceptor-side header runs 12V, COIN, GND, COUNTER and the MCU-side header runs GND, VCC, COIN, COUNTER, so the pin directly opposite 12V is GND. Read the silkscreen for every wire rather than counting rows across the board.

Which of the two boards is the one I program?

Neither. There is no microcontroller in this box — the module has a power converter and protection on it, and the acceptor has its own fixed firmware you configure with its three buttons. Your own ESP32, UNO or Pico is the third thing, and you supply it.

Alongside this page

The rest of the Amazon store, and which boxes have handbooks

Where this goes next

Why the guide is so insistent about the adapter, and what a laptop port actually does.

One USB-C cable, and the 2 A rule →

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