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adxl345: Compress each sample from 6 bytes to 5 bytes

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Transmit data from mcu to host using 5 bytes per sample and up to 10
samples per message block.  This improves bandwidth efficiency.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor
2021-08-22 16:24:16 -04:00
parent e34137582d
commit 22167f9510
2 changed files with 54 additions and 20 deletions
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44
klippy/extras/adxl345.py
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@@ -21,6 +21,7 @@ QUERY_RATES = {
}
ADXL345_DEV_ID = 0xe5
SET_FIFO_CTL = 0x90
FREEFALL_ACCEL = 9.80665 * 1000.
SCALE = 0.0039 * FREEFALL_ACCEL # 3.9mg/LSB * Earth gravity in mm/s**2
@@ -205,6 +206,9 @@ class ClockSyncRegression:
MIN_MSG_TIME = 0.100
BYTES_PER_SAMPLE = 5
SAMPLES_PER_BLOCK = 10
# Printer class that controls ADXL345 chip
class ADXL345:
def __init__(self, config):
@@ -236,7 +240,8 @@ class ADXL345:
mcu.register_config_callback(self._build_config)
mcu.register_response(self._handle_adxl345_data, "adxl345_data", oid)
# Clock tracking
self.last_sequence = self.last_limit_count = self.max_query_duration = 0
self.last_sequence = self.max_query_duration = 0
self.last_limit_count = self.last_error_count = 0
self.clock_sync = ClockSyncRegression(self.mcu, 640)
# API server endpoints
self.api_dump = motion_report.APIDumpHelper(
@@ -285,24 +290,31 @@ class ADXL345:
time_base, chip_base, inv_freq = self.clock_sync.get_time_translation()
# Process every message in raw_samples
count = seq = 0
samples = [None] * (len(raw_samples) * 8)
samples = [None] * (len(raw_samples) * SAMPLES_PER_BLOCK)
for params in raw_samples:
seq_diff = (last_sequence - params['sequence']) & 0xffff
seq_diff -= (seq_diff & 0x8000) << 1
seq = last_sequence - seq_diff
d = bytearray(params['data'])
len_d = len(d)
sdata = [(d[i] | ((d[i+1] & 0x1f) << 8)) - ((d[i+1] & 0x10) << 9)
for i in range(0, len_d-1, 2)]
msg_cdiff = seq * 8 - chip_base
for i in range(len_d // 6):
x = round(sdata[i*3 + x_pos] * x_scale, 6)
y = round(sdata[i*3 + y_pos] * y_scale, 6)
z = round(sdata[i*3 + z_pos] * z_scale, 6)
msg_cdiff = seq * SAMPLES_PER_BLOCK - chip_base
for i in range(len(d) // BYTES_PER_SAMPLE):
d_xyz = d[i*BYTES_PER_SAMPLE:(i+1)*BYTES_PER_SAMPLE]
xlow, ylow, zlow, xzhigh, yzhigh = d_xyz
if yzhigh & 0x80:
self.last_error_count += 1
continue
rx = (xlow | ((xzhigh & 0x1f) << 8)) - ((xzhigh & 0x10) << 9)
ry = (ylow | ((yzhigh & 0x1f) << 8)) - ((yzhigh & 0x10) << 9)
rz = ((zlow | ((xzhigh & 0xe0) << 3) | ((yzhigh & 0xe0) << 6))
- ((yzhigh & 0x40) << 7))
raw_xyz = (rx, ry, rz)
x = round(raw_xyz[x_pos] * x_scale, 6)
y = round(raw_xyz[y_pos] * y_scale, 6)
z = round(raw_xyz[z_pos] * z_scale, 6)
ptime = round(time_base + (msg_cdiff + i) * inv_freq, 6)
samples[count] = (ptime, x, y, z)
count += 1
self.clock_sync.set_last_chip_clock(seq * 8 + i)
self.clock_sync.set_last_chip_clock(seq * SAMPLES_PER_BLOCK + i)
del samples[count:]
return samples
def _update_clock(self, minclock=0):
@@ -332,7 +344,8 @@ class ADXL345:
self.mcu.seconds_to_clock(.000005))
return
self.max_query_duration = 2 * duration
msg_count = sequence * 8 + buffered // 6 + fifo
msg_count = (sequence * SAMPLES_PER_BLOCK
+ buffered // BYTES_PER_SAMPLE + fifo)
# The "chip clock" is the message counter plus .5 for average
# inaccuracy of query responses and plus .5 for assumed offset
# of adxl345 hw processing time.
@@ -352,7 +365,7 @@ class ADXL345:
self.set_reg(REG_DATA_FORMAT, 0x0B)
self.set_reg(REG_FIFO_CTL, 0x00)
self.set_reg(REG_BW_RATE, QUERY_RATES[self.data_rate])
self.set_reg(REG_FIFO_CTL, 0x80)
self.set_reg(REG_FIFO_CTL, SET_FIFO_CTL)
# Setup samples
with self.lock:
self.raw_samples = []
@@ -367,7 +380,7 @@ class ADXL345:
logging.info("ADXL345 starting '%s' measurements", self.name)
# Initialize clock tracking
self.last_sequence = 0
self.last_limit_count = 0
self.last_limit_count = self.last_error_count = 0
self.clock_sync.reset(reqclock, 0)
self.max_query_duration = 1 << 31
self._update_clock(minclock=reqclock)
@@ -392,7 +405,8 @@ class ADXL345:
samples = self._extract_samples(raw_samples)
if not samples:
return {}
return {'data': samples, 'overflows': self.last_limit_count}
return {'data': samples, 'errors': self.last_error_count,
'overflows': self.last_limit_count}
def _api_startstop(self, is_start):
if is_start:
self._start_measurements()