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heater: Force set_pwm of zero when target_temp is zero 

Fix a corner case where a residual in the PID could cause a non-zero
pwm request even when the target_temp is zero.  (Which could lead to a
firmware "Missed scheduling of next pwm event" shutdown.)

Simplify the logic for suppressing duplicate pwm updates and make sure
a zero target_temp always results in a zero pwm update on the
following set_pwm calculation.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2017-03-13 13:13:31 -04:00
parent f66b1ac450
commit e60779bfe1
1 changed files with 5 additions and 8 deletions
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13
klippy/heater.py
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@ -72,14 +72,11 @@ class PrinterHeater:
self.next_pwm_time = 0.
self.last_pwm_value = 0
def set_pwm(self, read_time, value):
if value:
if self.target_temp <= 0.:
return
if (read_time < self.next_pwm_time
and abs(value - self.last_pwm_value) < 0.05):
return
elif not self.last_pwm_value and (
self.target_temp <= 0. or read_time < self.next_pwm_time):
if self.target_temp <= 0.:
value = 0.
if ((read_time < self.next_pwm_time or not self.last_pwm_value)
and abs(value - self.last_pwm_value) < 0.05):
# No significant change in value - can suppress update
return
pwm_time = read_time + REPORT_TIME + SAMPLE_TIME*SAMPLE_COUNT
self.next_pwm_time = pwm_time + 0.75 * MAX_HEAT_TIME