This page discusses the different hardware boards and assemblies associated with the Tooltron system. We will also cover mounting considerations for toolboards.


There are two PCBs in the tooltron system. The first is the cardbox, which handles tool selection. The second is the toolbox, which controls the tools themselves.


The cardbox simply uses a matrix keyboard. It has 4 x 4 lines for the keyboard which must be strobed to read the rows and columns. There are also 3 LEDs which are controlled by the microcontroller. We currently use an ATMega168 for control.

The board incorporates a USB to RS485 converter. The USB connector bring in both unregulated power greater than 5V and the USB data. The RS485 converter is not designed to remove local echo so this must be handled by the server software. Also be aware that there is no arbitration on the converter side so ensure that no one is sending before sending from the server.

The ATMega168 is hooked up to the RS485 network. It must access the network similarly to the Toolboxes.


The toolbox is an ATTiny2313 powered over the RS485/Power. It takes in RS422 to communicate to the network but only implements half duplex as full duplex is never needed on the network. The microcontroller drives the 3 LEDs as well as reads the two buttons. This is all done in software with no hardware debouncing. The AC power detection to see if the tool is running is handeled by a separate IC (MID400) which outputs a digital signal to the ATTiny. An override pin is supplied to bypass the microcontroller in regards to the transistor that enables/disables the relay. By shorting the override pins (one is VCC, the other is the gate to the transistor), the relay can be set to always on. For security reasons we attach this to a keyed switch and epoxy the entire wiring harness together so that it is non-trivial to remove. The relay is sized to handle 220VAC and power a large lathe. As always, check the power requirements of the tool before wiring it up. To ensure that the AC detection circuitry can handle different input voltages, one must size the resistor connecting the AC line to the AC detection IC correctly. Details of this are in the MID400 datasheet.

Wiring Harnesses

There are several wiring harnesses for Tooltron. The pinouts (in the correct order) are shown below. The board is designed to use C-Grid, female connectors to the board.

Toolbox LED/Button Harness
Red LED - Yellow LED - Green LED - Green Button Red Button
Red LED + Yellow LED + Green LED + GND GND
Cardbox LED Button Harness
LED Green - LED Yellow - LED Red -
LED Green + LED Yellow + LED Red +
Cardbox Keypad Harness
Keypad Col 1 Keypad Col 2 Keypad Col 3 Keypad Col 4 Keypad Row 1 Keypad Row 2 Keypad Row 3 Keypad Row 4
Power/RS422 Harness
Vin RS422 B GND
Blank RS422 A Blank
Power/USB Harness
Blank USB D- Blank

BNC Plug (Male end, facing the plug)

  • Note that there are only four pins. We are trying to emulate the shape of the plug with the table
RS422B RS422A