Invert Chamber heater signal

[Rom]

Hi! I have chamber heater on pin8 (Heater3), but it logical 0 active. Can I invert signal in G-Codes or somewhere else by software? I have ULN2003 connected to pin8 and Chamber power on by command M141 S0, and power off by M141 S100.

[dc42]

In RepRapFirmware 3 you can invert any pin, see https://duet3d.dozuki.com/Wiki/RepRapFirmware_3_overview.

Caution, the heater outputs are pulled high at power up by the internal pullup resistor in the MCU. That's why we used active low signals. You can defeat the internal pullup using a pulldown resistor. Suitable values are 2.2K to 4.7K.

[Rom]

will try it. thank's!