Merge pull request #2447 from leptun/MK3_BED_LEVELING_PWM

Turn off bed while probing during MBL

Firmware/heatbed_pwm.cpp

@@ -45,6 +45,12 @@
 // If there are any change requirements in the future, the signal must be checked with an osciloscope again,
 // ad-hoc changes may completely screw things up!
 
+// 2020-01-29 update: we are introducing a new option to the automaton that will allow us to force the output state
+// to either full ON or OFF. This is so that interference during the MBL probing is minimal.
+// To accomplish this goal we use bedPWMDisabled. It is only supposed to be used for brief periods of time as to
+// not make the bed temperature too unstable. Also, careful consideration should be used when using this
+// option as leaving this enabled will also keep the bed output in the state it stopped in.
+
 ///! Definition off finite automaton states
 enum class States : uint8_t {
 	ZERO_START = 0,///< entry point of the automaton - reads the soft_pwm_bed value for the next whole PWM cycle
@@ -61,6 +67,8 @@ enum class States : uint8_t {
 ///! Inner states of the finite automaton
 static States state = States::ZERO_START;
 
+bool bedPWMDisabled = 0;
+
 ///! Fast PWM counter is used in the RISE and FALL states (62.5kHz)
 static uint8_t slowCounter = 0;
 ///! Slow PWM counter is used in the ZERO and ONE states (62.5kHz/8 or 64)
@@ -93,6 +101,7 @@ ISR(TIMER0_OVF_vect)          // timer compare interrupt service routine
 {
 	switch(state){
 	case States::ZERO_START:
+		if (bedPWMDisabled) return; // stay in the OFF state and do not change the output pin
 		pwm = soft_pwm_bed << 1;// expecting soft_pwm_bed to be 7bit!
 		if( pwm != 0 ){
 			state = States::ZERO;     // do nothing, let it tick once again after the 30Hz period
@@ -136,6 +145,7 @@ ISR(TIMER0_OVF_vect)          // timer compare interrupt service routine
 		break;
 	case States::ONE:             // state ONE - we'll either stay in ONE or change to FALL
 		OCR0B = 255;
+		if (bedPWMDisabled) return; // stay in the ON state and do not change the output pin
 		slowCounter += slowInc;   // this does software timer_clk/256 or less
 		if( slowCounter < pwm ){
 			return;

Firmware/mesh_bed_calibration.cpp

@@ -6,6 +6,7 @@
 #include "mesh_bed_leveling.h"
 #include "stepper.h"
 #include "ultralcd.h"
+#include "temperature.h"
 
 #ifdef TMC2130
 #include "tmc2130.h"
@@ -946,6 +947,7 @@ inline bool find_bed_induction_sensor_point_z(float minimum_z, uint8_t n_iter, i
         )
 {
 	bool high_deviation_occured = false; 
+    bedPWMDisabled = 1;
 #ifdef TMC2130
 	FORCE_HIGH_POWER_START;
 #endif
@@ -1044,6 +1046,7 @@ inline bool find_bed_induction_sensor_point_z(float minimum_z, uint8_t n_iter, i
 #ifdef TMC2130
 	FORCE_HIGH_POWER_END;
 #endif
+    bedPWMDisabled = 0;
 	return true;
 
 error:
@@ -1053,6 +1056,7 @@ error:
 #ifdef TMC2130
 	FORCE_HIGH_POWER_END;
 #endif
+    bedPWMDisabled = 0;
 	return false;
 }
 

Firmware/temperature.cpp

@@ -1403,6 +1403,7 @@ void disable_heater()
     target_temperature_bed=0;
     soft_pwm_bed=0;
 	timer02_set_pwm0(soft_pwm_bed << 1);
+	bedPWMDisabled = 0;
     #if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
       //WRITE(HEATER_BED_PIN,LOW);
     #endif

Firmware/temperature.h

@@ -84,6 +84,8 @@ extern int current_voltage_raw_IR;
   extern unsigned char soft_pwm_bed;
 #endif
 
+extern bool bedPWMDisabled;
+
 #ifdef PIDTEMP
   extern int pid_cycle, pid_number_of_cycles;
   extern float Kc,_Kp,_Ki,_Kd;