M106 and M145 give you a lot of control over these things. The code is shown below.
#if FAN_COUNT > 0
/**
* M106: Set Fan Speed
*
* S Speed between 0-255
* P Fan index, if more than one fan
*/
inline void gcode_M106() {
uint16_t s = code_seen('S') ? code_value_ushort() : 255,
p = code_seen('P') ? code_value_ushort() : 0;
NOMORE(s, 255);
if (p < FAN_COUNT) fanSpeeds[p] = s;
}
/**
* M107: Fan Off
*/
inline void gcode_M107() {
uint16_t p = code_seen('P') ? code_value_ushort() : 0;
if (p < FAN_COUNT) fanSpeeds[p] = 0;
}
#endif // FAN_COUNT > 0
/**
* M145: Set the heatup state for a material in the LCD menu
* S (0=PLA, 1=ABS)
* H
* B
* F
*/
inline void gcode_M145() {
int8_t material = code_seen('S') ? (int8_t)code_value_int() : 0;
if (material < 0 || material > 1) {
SERIAL_ERROR_START;
SERIAL_ERRORLNPGM(MSG_ERR_MATERIAL_INDEX);
}
else {
int v;
switch (material) {
case 0:
if (code_seen('H')) {
v = code_value_int();
plaPreheatHotendTemp = constrain(v, EXTRUDE_MINTEMP, HEATER_0_MAXTEMP - 15);
}
if (code_seen('F')) {
v = code_value_int();
plaPreheatFanSpeed = constrain(v, 0, 255);
}
#if TEMP_SENSOR_BED != 0
if (code_seen('B')) {
v = code_value_int();
plaPreheatHPBTemp = constrain(v, BED_MINTEMP, BED_MAXTEMP - 15);
}
#endif
break;
case 1:
if (code_seen('H')) {
v = code_value_int();
absPreheatHotendTemp = constrain(v, EXTRUDE_MINTEMP, HEATER_0_MAXTEMP - 15);
}
if (code_seen('F')) {
v = code_value_int();
absPreheatFanSpeed = constrain(v, 0, 255);
}
#if TEMP_SENSOR_BED != 0
if (code_seen('B')) {
v = code_value_int();
absPreheatHPBTemp = constrain(v, BED_MINTEMP, BED_MAXTEMP - 15);
}
#endif
break;
}
}
}