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tmc2130: Rework current selection to prefer vsense=1

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It is preferable to program the tmc drivers with an irun (or cs)
setting near 31, as otherwise the driver may have reduced microstep
precision.  It was possible for the driver to be programmed with
irun=16 or irun=17 when it could have been configured with irun=31
with vsense=1 instead.  This would occur on tmc2130/tmc2208/tmc2209
drivers for values around 0.900 to 1.000 amps (when using a typical
sense_resistor settings of 0.110 Ohms).

Change the code to prefer using vsense=1 to avoid this issue.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor
2022-01-12 23:43:11 -05:00
parent 89b4fecac4
commit 34a1ce4837
3 changed files with 45 additions and 27 deletions
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41
klippy/extras/tmc2130.py
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@@ -116,30 +116,33 @@ class TMCCurrentHelper:
vref = 0.32
if vsense:
vref = 0.18
cs = int(32. * current * sense_resistor * math.sqrt(2.) / vref
- 1. + .5)
cs = int(32. * sense_resistor * current * math.sqrt(2.) / vref + .5) - 1
return max(0, min(31, cs))
def _calc_current(self, run_current, hold_current):
vsense = False
irun = self._calc_current_bits(run_current, vsense)
ihold = self._calc_current_bits(min(hold_current, run_current),
vsense)
if irun < 16 and ihold < 16:
vsense = True
irun = self._calc_current_bits(run_current, vsense)
ihold = self._calc_current_bits(min(hold_current, run_current),
vsense)
return vsense, irun, ihold
def _calc_current_from_field(self, field_name):
bits = self.fields.get_field(field_name)
def _calc_current_from_bits(self, cs, vsense):
sense_resistor = self.sense_resistor + 0.020
vref = 0.32
if self.fields.get_field("vsense"):
if vsense:
vref = 0.18
return (bits + 1) * vref / (32 * sense_resistor * math.sqrt(2.))
return (cs + 1) * vref / (32. * sense_resistor * math.sqrt(2.))
def _calc_current(self, run_current, hold_current):
vsense = True
irun = self._calc_current_bits(run_current, True)
if irun == 31:
cur = self._calc_current_from_bits(irun, True)
if cur < run_current:
irun2 = self._calc_current_bits(run_current, False)
cur2 = self._calc_current_from_bits(irun2, False)
if abs(run_current - cur2) < abs(run_current - cur):
vsense = False
irun = irun2
ihold = self._calc_current_bits(min(hold_current, run_current), vsense)
return vsense, irun, ihold
def get_current(self):
run_current = self._calc_current_from_field("irun")
hold_current = self._calc_current_from_field("ihold")
irun = self.fields.get_field("irun")
ihold = self.fields.get_field("ihold")
vsense = self.fields.get_field("vsense")
run_current = self._calc_current_from_bits(irun, vsense)
hold_current = self._calc_current_from_bits(ihold, vsense)
return run_current, hold_current, self.req_hold_current, MAX_CURRENT
def set_current(self, run_current, hold_current, print_time):
self.req_hold_current = hold_current