我现在正在使用mpu9250作为我的硕士论文，但是我对硬件设备还是很陌生。我的目标是以采样率收集数据并通过Allan偏差对这些数据进行后处理。所以我只想从512字节fifo中获取数据，但是当我尝试读取数据时，它总是溢出，这使我很烦。
我知道该方法是将读取速度设置为高于fifo写入速度，因此我消除了循环中的睡眠时间，但似乎比以前更快地溢出了。我有点困惑，因为读取速度取决于写入速度。
#!/usr/bin/env python3
import os
import time
import sys
import struct
import csv
from datetime import datetime
from mpu9250_FIFO import MPU9250
from navio.leds import Led
def main():
# Initialize MPU9250
mpu = MPU9250()
mpu.bus_open(max_speed_hz=10000000) # Hz
sampleRate = 50
sampleRateDiv = int(1000 / sampleRate - 1)
mpu.initialize(sample_rate_div=sampleRateDiv, low_pass_filter_gt=0x01, low_pass_filter_a=0x01)
mpu.set_acc_scale(0x08) # +/-4G
mpu.set_gyro_scale(0x08) # +/-500dps
# Enable FIFO to collect data
mpu.enableFIFO(True)
# Test connection:
if mpu.testConnection():
print("Connection working.")
else:
print("Connection to one of the sensors is faulty.")
now = datetime.now().strftime('%d-%m-%Y_%H:%M:%S')
fname = '/home/pi/Python/meas_data/mpu9250_data_' + now + r'.txt'
with open(fname, 'w', 1) as data_imu:
# write headers to file
data_imu.write('Sample Rate: %d Hz\n' % sampleRate)
data_imu.write('mpu_accel_1, mpu_accel_2, mpu_accel_3, mpu_gyro_1, mpu_gyro_2, mpu_gyro_3, temp\n')
#print("----1----")
# Main loop
while True:
mpudata_a, mpudata_g, mpudata_temp = mpu.getFIFOData()
#print("----2----")
data = mpudata_a + mpudata_g + mpudata_temp
# print(data)
data_imu.write(str(data).replace("[", "").replace("]", "") + "\n")
# FIFO READ AND WRITE
# FIFO_R_W REGISTER:
# This register is used to read and write data from the FIFO buffer. Data is written to the FIFO
# in order of register number (from lowest to highest). If all the FIFO enable flags are enabled
# and all External Sensor Data registers (Registers 73 to 96) are associated with a Slave device,
# the contents of registers 59 through 96 will be written in order that the Sample Rate.
# The contents of the sensor data registers (Registers 59 to 96) are written into the FIFO buffer
# when their corresponding FIFO enable flags are set to 1 in FIFO_EN (Register 35). An additional
# flag for the sensor data registers associated with I2C Slave 3 can be found in I2C_MST_CTRL
# （Register 46).
# If the FIFO buffer has overflowed, the status bit FIFO_OFLOW_INT is automatically set to 1.
# This bit is located in INT_STATUS (Register 58). When the FIFO buffer has overflowed, the
# oldest data will be lost and new data will be written to the FIFO.
# If the FIFO buffer is empty, reading this register will return the last byte that was previously
# read from the FIFO until new data is available. The user should check FIFO_COUNT to ensure that
# the FIFO is not read when empty.
# -----------------------------------------------------------------------------------------------
def getFIFOData(self):
while True:
mpu_int_status = self.getIntStatus()
INT_FIFO_OFLOW_BIT = 0x10 # the 4th bit is set to 1 when FIFO buffer is overflowed
fifoCount = self.getFIFOCount()
#print("fifoCount:%d" % fifoCount)
if fifoCount < 14:
continue
# check for overflow (this shouldn't happen)
elif (mpu_int_status & 0x10 == 0x10) or fifoCount>=512:
print("fifoCount is: %d" % fifoCount)
print("FIFO is overflow!")
# print("Reset FIFO...")
# self.resetFIFO()
break
else:
packet_count = int(fifoCount/14)
# print("packet count:%d" % packet_count)
for i in range(0, packet_count):
response = self.ReadRegs(self.__MPUREG_FIFO_R_W, 14)
# print(response)
# Get Accelerometer values
for i in range(0, 3):
data = self.byte_to_float(response[i * 2:i * 2 + 2])
self.accelerometer_data[i] = self.G_SI * data / self.acc_divider
# print(self.accelerometer_data)
# Get temperature
i = 3
temp = self.byte_to_float(response[i * 2:i * 2 + 2])
self.temperature[i - 3] = (temp / 333.87) + 21.0
# print(self.temperature)
# Get gyroscope values
for i in range(4, 7):
data = self.byte_to_float(response[i * 2:i * 2 + 2])
self.gyroscope_data[i - 4] = (self.PI / 180) * data / self.gyro_divider
# print(self.gyroscope_data)
return self.accelerometer_data, self.gyroscope_data, self.temperature
def getIntStatus(self):
return self.ReadReg(self.__MPUREG_INT_STATUS)
def getFIFOCount(self):
response = self.ReadRegs(self.__MPUREG_FIFO_COUNTH, 2)
fifoCount = self.byte_to_float(response)
return fifoCount
def resetFIFO(self):
self.WriteReg(self.__MPUREG_USER_CTRL, 0x00)
self.WriteReg(self.__MPUREG_USER_CTRL, 0x04) # reset fifo mode
self.WriteReg(self.__MPUREG_USER_CTRL, 0x40) # FIFO_EN
print('fifo is reset!')
def enableFIFO(self, flag):
self.WriteReg(self.__MPUREG_FIFO_EN, 0x00)
if flag:
self.resetFIFO()
self.WriteReg(self.__MPUREG_FIFO_EN, 0xF8)
print('fifo is enabled!')
我希望得到恒定的fifo读数而不会溢出。