ldc1612: enable frequency div to reduce noise

BTT Eddy uses 12MHz clock in frequency.
Coil is oscillating at 3+MHz.
Which is out of spec for LDC1612 sensors.
Division of coil frequency seems to reduce output noise.

Signed-off-by: Timofey Titovets <[email protected]>

Author: nefelim4ag

klippy/extras/ldc1612.py

@@ -87,8 +87,12 @@ def __init__(self, config, calibration=None):
         self.oid = oid = mcu.create_oid()
         self.query_ldc1612_cmd = None
         self.ldc1612_setup_home_cmd = self.query_ldc1612_home_state_cmd = None
-        self.frequency = config.getint("frequency", DEFAULT_LDC1612_FREQ,
-                                       2000000, 40000000)
+        self.clock_freq = config.getint("frequency", DEFAULT_LDC1612_FREQ,
+                                        2000000, 40000000)
+        # Coil frequency divider, assume 12MHz is BTT Eddy
+        # BTT Eddy's coil frequency is > 1/4 of reference clock
+        self.sensor_div = 1 if self.clock_freq != DEFAULT_LDC1612_FREQ else 2
+        self.freq_conv = float(self.clock_freq * self.sensor_div) / (1<<28)
         if config.get('intb_pin', None) is not None:
             ppins = config.get_printer().lookup_object("pins")
             pin_params = ppins.lookup_pin(config.get('intb_pin'))
@@ -143,7 +147,7 @@ def add_client(self, cb):
     def setup_home(self, print_time, trigger_freq,
                    trsync_oid, hit_reason, err_reason):
         clock = self.mcu.print_time_to_clock(print_time)
-        tfreq = int(trigger_freq * (1<<28) / float(self.frequency) + 0.5)
+        tfreq = int(trigger_freq / self.freq_conv + 0.5)
         self.ldc1612_setup_home_cmd.send(
             [self.oid, clock, tfreq, trsync_oid, hit_reason, err_reason])
     def clear_home(self):
@@ -155,7 +159,7 @@ def clear_home(self):
         return self.mcu.clock_to_print_time(tclock)
     # Measurement decoding
     def _convert_samples(self, samples):
-        freq_conv = float(self.frequency) / (1<<28)
+        freq_conv = self.freq_conv
         count = 0
         for ptime, val in samples:
             mv = val & 0x0fffffff
@@ -176,11 +180,11 @@ def _start_measurements(self):
                 "(e.g. faulty wiring) or a faulty ldc1612 chip."
                 % (manuf_id, dev_id, LDC1612_MANUF_ID, LDC1612_DEV_ID))
         # Setup chip in requested query rate
-        rcount0 = self.frequency / (16. * self.data_rate)
+        rcount0 = self.clock_freq / (16. * self.data_rate)
         self.set_reg(REG_RCOUNT0, int(rcount0 + 0.5))
         self.set_reg(REG_OFFSET0, 0)
-        self.set_reg(REG_SETTLECOUNT0, int(SETTLETIME*self.frequency/16. + .5))
-        self.set_reg(REG_CLOCK_DIVIDERS0, (1 << 12) | 1)
+        self.set_reg(REG_SETTLECOUNT0, int(SETTLETIME*self.clock_freq/16. + .5))
+        self.set_reg(REG_CLOCK_DIVIDERS0, (self.sensor_div << 12) | 1)
         self.set_reg(REG_ERROR_CONFIG, (0x1f << 11) | 1)
         self.set_reg(REG_MUX_CONFIG, 0x0208 | DEGLITCH)
         self.set_reg(REG_CONFIG, 0x001 | (1<<12) | (1<<10) | (1<<9))