203 lines
8.6 KiB
Python
203 lines
8.6 KiB
Python
# Support for reading acceleration data from an mpu9250 chip
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#
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# Copyright (C) 2022 Harry Beyel <harry3b9@gmail.com>
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# Copyright (C) 2020-2021 Kevin O'Connor <kevin@koconnor.net>
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#
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# This file may be distributed under the terms of the GNU GPLv3 license.
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import logging
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from . import bus, adxl345, bulk_sensor
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MPU9250_ADDR = 0x68
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MPU_DEV_IDS = {
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0x74: "mpu-9515",
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0x73: "mpu-9255",
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0x71: "mpu-9250",
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0x70: "mpu-6500",
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0x68: "mpu-6050",
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#everything above are normal MPU IDs
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0x75: "mpu-unknown (DEFECTIVE! USE WITH CAUTION!)",
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0x69: "mpu-unknown (DEFECTIVE! USE WITH CAUTION!)",
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}
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# MPU9250 registers
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REG_DEVID = 0x75
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REG_FIFO_EN = 0x23
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REG_SMPLRT_DIV = 0x19
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REG_CONFIG = 0x1A
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REG_ACCEL_CONFIG = 0x1C
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REG_ACCEL_CONFIG2 = 0x1D
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REG_USER_CTRL = 0x6A
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REG_PWR_MGMT_1 = 0x6B
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REG_PWR_MGMT_2 = 0x6C
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SAMPLE_RATE_DIVS = { 4000:0x00 }
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SET_CONFIG = 0x01 # FIFO mode 'stream' style
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SET_ACCEL_CONFIG = 0x10 # 8g full scale
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SET_ACCEL_CONFIG2 = 0x08 # 1046Hz BW, 0.503ms delay 4kHz sample rate
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SET_PWR_MGMT_1_WAKE = 0x00
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SET_PWR_MGMT_1_SLEEP= 0x40
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SET_PWR_MGMT_2_ACCEL_ON = 0x07
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SET_PWR_MGMT_2_OFF = 0x3F
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FREEFALL_ACCEL = 9.80665 * 1000.
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# SCALE = 1/4096 g/LSB @8g scale * Earth gravity in mm/s**2
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SCALE = 0.000244140625 * FREEFALL_ACCEL
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FIFO_SIZE = 512
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MIN_MSG_TIME = 0.100
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BYTES_PER_SAMPLE = 6
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SAMPLES_PER_BLOCK = bulk_sensor.MAX_BULK_MSG_SIZE // BYTES_PER_SAMPLE
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BATCH_UPDATES = 0.100
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# Printer class that controls MPU9250 chip
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class MPU9250:
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def __init__(self, config):
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self.printer = config.get_printer()
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adxl345.AccelCommandHelper(config, self)
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self.axes_map = adxl345.read_axes_map(config)
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self.data_rate = config.getint('rate', 4000)
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if self.data_rate not in SAMPLE_RATE_DIVS:
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raise config.error("Invalid rate parameter: %d" % (self.data_rate,))
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# Setup mcu sensor_mpu9250 bulk query code
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self.i2c = bus.MCU_I2C_from_config(config,
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default_addr=MPU9250_ADDR,
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default_speed=400000)
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self.mcu = mcu = self.i2c.get_mcu()
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self.oid = oid = mcu.create_oid()
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self.query_mpu9250_cmd = None
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mcu.register_config_callback(self._build_config)
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self.bulk_queue = bulk_sensor.BulkDataQueue(mcu, oid=oid)
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# Clock tracking
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chip_smooth = self.data_rate * BATCH_UPDATES * 2
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self.clock_sync = bulk_sensor.ClockSyncRegression(mcu, chip_smooth)
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self.clock_updater = bulk_sensor.ChipClockUpdater(self.clock_sync,
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BYTES_PER_SAMPLE)
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self.last_error_count = 0
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# Process messages in batches
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self.batch_bulk = bulk_sensor.BatchBulkHelper(
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self.printer, self._process_batch,
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self._start_measurements, self._finish_measurements, BATCH_UPDATES)
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self.name = config.get_name().split()[-1]
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hdr = ('time', 'x_acceleration', 'y_acceleration', 'z_acceleration')
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self.batch_bulk.add_mux_endpoint("mpu9250/dump_mpu9250", "sensor",
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self.name, {'header': hdr})
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def _build_config(self):
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cmdqueue = self.i2c.get_command_queue()
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self.mcu.add_config_cmd("config_mpu9250 oid=%d i2c_oid=%d"
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% (self.oid, self.i2c.get_oid()))
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self.mcu.add_config_cmd("query_mpu9250 oid=%d clock=0 rest_ticks=0"
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% (self.oid,), on_restart=True)
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self.query_mpu9250_cmd = self.mcu.lookup_command(
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"query_mpu9250 oid=%c clock=%u rest_ticks=%u", cq=cmdqueue)
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self.clock_updater.setup_query_command(
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self.mcu, "query_mpu9250_status oid=%c", oid=self.oid, cq=cmdqueue)
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def read_reg(self, reg):
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params = self.i2c.i2c_read([reg], 1)
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return bytearray(params['response'])[0]
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def set_reg(self, reg, val, minclock=0):
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self.i2c.i2c_write([reg, val & 0xFF], minclock=minclock)
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def start_internal_client(self):
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aqh = adxl345.AccelQueryHelper(self.printer)
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self.batch_bulk.add_client(aqh.handle_batch)
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return aqh
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# Measurement decoding
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def _extract_samples(self, raw_samples):
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# Load variables to optimize inner loop below
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(x_pos, x_scale), (y_pos, y_scale), (z_pos, z_scale) = self.axes_map
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last_sequence = self.clock_updater.get_last_sequence()
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time_base, chip_base, inv_freq = self.clock_sync.get_time_translation()
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# Process every message in raw_samples
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count = seq = 0
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samples = [None] * (len(raw_samples) * SAMPLES_PER_BLOCK)
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for params in raw_samples:
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seq_diff = (params['sequence'] - last_sequence) & 0xffff
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seq_diff -= (seq_diff & 0x8000) << 1
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seq = last_sequence + seq_diff
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d = bytearray(params['data'])
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msg_cdiff = seq * SAMPLES_PER_BLOCK - chip_base
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for i in range(len(d) // BYTES_PER_SAMPLE):
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d_xyz = d[i*BYTES_PER_SAMPLE:(i+1)*BYTES_PER_SAMPLE]
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xhigh, xlow, yhigh, ylow, zhigh, zlow = d_xyz
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# Merge and perform twos-complement
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rx = ((xhigh << 8) | xlow) - ((xhigh & 0x80) << 9)
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ry = ((yhigh << 8) | ylow) - ((yhigh & 0x80) << 9)
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rz = ((zhigh << 8) | zlow) - ((zhigh & 0x80) << 9)
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raw_xyz = (rx, ry, rz)
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x = round(raw_xyz[x_pos] * x_scale, 6)
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y = round(raw_xyz[y_pos] * y_scale, 6)
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z = round(raw_xyz[z_pos] * z_scale, 6)
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ptime = round(time_base + (msg_cdiff + i) * inv_freq, 6)
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samples[count] = (ptime, x, y, z)
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count += 1
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self.clock_sync.set_last_chip_clock(seq * SAMPLES_PER_BLOCK + i)
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del samples[count:]
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return samples
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# Start, stop, and process message batches
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def _start_measurements(self):
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# In case of miswiring, testing MPU9250 device ID prevents treating
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# noise or wrong signal as a correctly initialized device
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dev_id = self.read_reg(REG_DEVID)
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if dev_id not in MPU_DEV_IDS.keys():
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raise self.printer.command_error(
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"Invalid mpu id (got %x).\n"
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"This is generally indicative of connection problems\n"
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"(e.g. faulty wiring) or a faulty chip."
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% (dev_id))
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else:
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logging.info("Found %s with id %x"% (MPU_DEV_IDS[dev_id], dev_id))
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# Setup chip in requested query rate
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self.set_reg(REG_PWR_MGMT_1, SET_PWR_MGMT_1_WAKE)
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self.set_reg(REG_PWR_MGMT_2, SET_PWR_MGMT_2_ACCEL_ON)
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# Add 20ms pause for accelerometer chip wake up
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self.read_reg(REG_DEVID) # Dummy read to ensure queues flushed
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systime = self.printer.get_reactor().monotonic()
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next_time = self.mcu.estimated_print_time(systime) + 0.020
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self.set_reg(REG_SMPLRT_DIV, SAMPLE_RATE_DIVS[self.data_rate],
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minclock=self.mcu.print_time_to_clock(next_time))
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self.set_reg(REG_CONFIG, SET_CONFIG)
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self.set_reg(REG_ACCEL_CONFIG, SET_ACCEL_CONFIG)
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self.set_reg(REG_ACCEL_CONFIG2, SET_ACCEL_CONFIG2)
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# Start bulk reading
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self.bulk_queue.clear_samples()
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systime = self.printer.get_reactor().monotonic()
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print_time = self.mcu.estimated_print_time(systime) + MIN_MSG_TIME
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reqclock = self.mcu.print_time_to_clock(print_time)
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rest_ticks = self.mcu.seconds_to_clock(4. / self.data_rate)
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self.query_mpu9250_cmd.send([self.oid, reqclock, rest_ticks],
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reqclock=reqclock)
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logging.info("MPU9250 starting '%s' measurements", self.name)
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# Initialize clock tracking
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self.clock_updater.note_start()
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self.last_error_count = 0
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def _finish_measurements(self):
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# Halt bulk reading
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self.query_mpu9250_cmd.send_wait_ack([self.oid, 0, 0])
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self.bulk_queue.clear_samples()
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logging.info("MPU9250 finished '%s' measurements", self.name)
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self.set_reg(REG_PWR_MGMT_1, SET_PWR_MGMT_1_SLEEP)
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self.set_reg(REG_PWR_MGMT_2, SET_PWR_MGMT_2_OFF)
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def _process_batch(self, eventtime):
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self.clock_updater.update_clock()
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raw_samples = self.bulk_queue.pull_samples()
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if not raw_samples:
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return {}
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samples = self._extract_samples(raw_samples)
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if not samples:
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return {}
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return {'data': samples, 'errors': self.last_error_count,
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'overflows': self.clock_updater.get_last_overflows()}
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def load_config(config):
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return MPU9250(config)
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def load_config_prefix(config):
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return MPU9250(config)
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