RepRapFirmware allows you to connect other devices to unused outputs. Expansion boards also provide additional inputs and outputs. The following Gcodes allow re-purposing of some pins, and direct control of those pins for peripherals such as PWM hobby servos, DC motors and pumps.
There are a number of options for extra control:
| Duet 3 MB6HC/6XD | Duet 3 Mini 5+ | Duet 2 WiFi/Ethernet | Duet 2 Maestro | Notes | |
|---|---|---|---|---|---|
| MaxGpInPorts | 32 (16 in RRF3.3) | 32 (16 in RRF3.3) | 20 | 10 | The maximum number of general purpose input ports. |
| MaxGpOutPorts | 32 | 32 | 20 | 10 | The maximum number of general purpose output ports |
In RepRapFirmware 3.x, define the fan connector with M950 as a general purpose I/O pin that can be controlled using M42.
In RepRapFirmware 2.x, using the I-1 parameter in the M106 command for a fan disables it, which frees up the pin for use as a general purpose I/O pin that can be controlled using M42.
In RRF 3.x and later, pins are undefined at startup and no GPIO ports are allocated by default. Create a GPIO port using M950. Control the port using M42 or M280, where the P parameter is the GPIO port number. Duet 2 supports up to 10 GPIO ports, numbered 0 to 9.
In RRF_3, the F and I parameters are no longer supported in M42. Instead, use the F and I parameters in M950 when you create the GPIO port.
Example - RRF_2 code:
M42 P3 I1 S0.5 F500 ; set Heater 3 pin to 50% PWM at 500Hz
RRF_3 code:
M950 P0 C"exp.heater3" Q500 ; allocate GPIO port 0 to heater3 on expansion connector, 500Hz
...
M42 P0 S0.5 ; set 50% PWM on GPIO port 0
For a list of pin names, see RRF3 Pin names.
The rest of this page shows how to set up M42 and M280 in RRF 2.x.
Starting with firmware version 1.16, pin numbers in the M42 command are logical pin numbers, not Arduino-like pin numbers. The M280 servo control uses a subset of the same pin numbers.
Note that these logical pin numbers are not the physical pin numbers on the expansion header, or the internal pin numbering within the firmware.
To see a list of logical pin numbers, and where these pins are on the 2nd Generation Duets, see the input/output section and wiring diagram on the Duet 2 WiFi and Ethernet hardware overview and Duet 2 Maestro hardware overview pages.