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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 (or yellow, if there is no red wire) and black wires: connect them to
the + and - pins respectively of an always-on fan output signalconnector.

Blue wire (PWM control): connect it
to be inverted if its valuethe FAN- pin of your chosen controlled fan connector.

Tacho wire (whatever wire
is greater than zero.left, usually green or yellow): optionally, connect it to the cathode of a small signal diode (1N4148 should be 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 it 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 (or yellow, if there is no red wire) and black wires: connect them to
the + and - pins respectively of an always-on fan output signalconnector.

Blue wire (PWM control): connect it
to be inverted if its valuethe FAN- pin of your chosen controlled fan connector.

Tacho wire (whatever wire
is greater than zero.left, usually green or yellow): optionally, connect it to the cathode of a small signal diode (1N4148 should be 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 it 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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