This article describes connectors on the Original Prusa MK4, which can be used to connect your own or any 3rd party accessory.
Warning: Keep in mind the maximum allowable electric current (I) and voltage (V) limits. Failure to do so may result in permanent damage to the board. This article is intended for experienced users only!
xBuddy
| Connector | Pin | Type | Function | GPIO | Limitations |
|---|---|---|---|---|---|
| J29 (ACCELEROMETER) |
1 | open drain output | SPI2 CS | PA10 | max 3.3V/5mA |
| J29 (ACCELEROMETER) | 2 | input/output | SPI2 SCL | PB10 | max 5V/5mA |
| J29 (ACCELEROMETER) | 3 | input/output | SPI2 SDI | PC3 | max 5V/5mA |
| J29 (ACCELEROMETER) | 4 | input/output | SPI2 SDO | PC2 | max 5V/5mA |
| J29 (ACCELEROMETER) | 5 | 3V3 | POWER | X | max 50mA |
| J29 (ACCELEROMETER) | 6 | GND | POWER | X | - |
| J23 (I2C) | 1 | input/output | I2C2 SCL | PF1 | max 5V/5mA |
| J23 (I2C) | 2 | input/output | I2C2 SDA | PF0 | max 5V/5mA |
| J23 (I2C) | 3 | 3V3 | POWER | X | max 50mA |
| J23 (I2C) | 4 | GND | POWER | X | - |
| J15(A_TEMP) | 1 | analog input | THERM 3 | PF5 | max 3.3V |
| J15(A_TEMP) | 2 | GND | POWER | X | - |
| J6 (MMU) | 1 | input/output | USART6 TX | PC6 | max 5V/5mA |
| J6 (MMU) | 2 | RS485- | USART6 | X | max 3.3V/250mA |
| J6 (MMU) | 3 | input/output | USART6 RX | PC7 | max 5V/5mA |
| J6 (MMU) | 4 | RS485+ | USART6 | X | max 3.3V/250mA |
| J6 (MMU) | 5 | MMU 5V (switchable) | POWER | PG2 | max 5V/0.5A |
| J6 (MMU) | 6 | open drain output | MMU RESET | PG8 | max 5V/5mA |
| J6 (MMU) | 7 | GND | POWER | X | - |
| J6 (MMU) | 8 | output | nAC FAULT | X | max 3.3V/5mA |
| J6 (MMU) | 9 | GND | POWER | X | - |
| J6 (MMU) | 10 | MMU 24V (switchable) | POWER | PG2 | max 24V/3.6A |
| J6 (MMU) | 11 | GND | POWER | X | - |
| J6 (MMU) | 12 | MMU 24V (switchable) | POWER | PG2 | max 24V/3.6A |
xLCD
| Connector | Pin | Type | Function | GPIO | Limitations |
|---|---|---|---|---|---|
| P11 | 1 | 3.3V | POWER | - | max 3.3V/50mA |
| P11 | 2 | open drain output | LCD 1wire | PD11 | max 5V/18.5mA |
| P11 | 3 | input/output | I2C3 SCL | PA8 | max 3.3V/5mA |
| P11 | 4 | input/output | I2C3 SDA | PC9 | max 3.3V/5mA |
| P11 | 5 | GND | POWER | X | - |
| P11 | 6 | 5V | POWER | X | max 5V/100mA |
5 comments
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Fil4ment
•
Of note: the firmware does not currently support defining any of these pins as analog outputs, for use with the M42 command. Even though several are capable of supporting the PWM output.
Fil4ment
•
Just FYI, for those in the future: I think the answer is well documented in this thread. Short version is that they've released the schematic here, and the marlin gCode addressing of pins should follow the following scheme: "#define MARLIN_PORT_PIN(port, pin) ((16 * (port)) + (pin))" With Port A=0, B=1, etc.
Fil4ment
•
From the recently released schematic, we need PA15, PE2-PE6, PE12, and if possible to use, nAC_FAULT
Fil4ment
•
I also am interested to know the M42 P-numbers for these pins, as well as the "expansion" (J9?) header, if we can get those numbers as well. Previously reverse engineered to be PE2-PE5, PA15, and PF8. Would much prefer to use pins that aren't already being used for anything else in the ecosystem.