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Revision to Connecting and configuring fans

David Crocker

For more examples see the [[ConfiguringRepRapFirmwareCartesianPrinter#Section_Tool_definition_section|tool definition section]] of the config.g file.
 
== Connecting 4 wire fans and inverting the PWM signal ==
== Connecting 4 wire fans and inverting the PWM signal ==
 
The I parameter on M106 causes4-wire fans have a separate PWM input wire. The recommended connections are:

Red and black wires: connect them to
the + and - pins respectively of an always-on fan output signalconnector

Blue wire (PWM control): connect it
to the FAN- pin of your chosen controlled fan connector

Yellow wire (tacho output): optionally, connect it to the cathode of a small signal diode (1N4148 should
be inverted if its value is greater than zero.OK) and connect the anode of the diode to pin PB6 on the expansion connector, to provide a reading of the fan RPM. Or you can leave the yellow wire not connected.

In the M106 command for that fan, use the I1 parameter to correct the PWM sense, e.g.:
The I parameter on M106 causes4-wire fans have a separate PWM input wire. The recommended connections are:

Red and black wires: connect them to
the + and - pins respectively of an always-on fan output signalconnector

Blue wire (PWM control): connect it
to the FAN- pin of your chosen controlled fan connector

Yellow wire (tacho output): optionally, connect it to the cathode of a small signal diode (1N4148 should
be inverted if its value is greater than zero.OK) and connect the anode of the diode to pin PB6 on the expansion connector, to provide a reading of the fan RPM. Or you can leave the yellow wire not connected.

In the M106 command for that fan, use the I1 parameter to correct the PWM sense, e.g.:
 
[code]M106 P1 I1 ; invert PWM of fan 1[/code]
 
This makes the cooling fan output suitable for feeding the PWM input of== Using a 4-wire fan viaconnector as a diode. If general purpose output ==

If you use
the I-1 parameter is present and zero,in the output is not inverted. If the I parameter is negativem106 command fort a fan then in RRF 1.16 and later the fan is disabled, which frees up the pin for use as a general purpose I/O pin that can be controlled using M42.
This makes the cooling fan output suitable for feeding the PWM input of== Using a 4-wire fan viaconnector as a diode. If general purpose output ==

If you use
the I-1 parameter is present and zero,in the output is not inverted. If the I parameter is negativem106 command fort a fan then in RRF 1.16 and later the fan is disabled, which frees up the pin for use as a general purpose I/O pin that can be controlled using M42.

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