ADXL345 Device ID and offset being wrong (Raspberry Pi)

问题

Currently using 3 Raspberry Pi's. Each one of them should be able to collect x, y and z with an accelerometer. However a problem is occuring when I run the following script on my newest Raspberry Pi:

#!/usr/bin/python
# -*- coding: utf-8 -*-
# Example on how to read the ADXL345 accelerometer.
# Kim H. Rasmussen, 2014
import sys, math, os, spidev, datetime, ftplib

# Setup SPI
spi = spidev.SpiDev()
#spi.mode = 3    <-- Important: Do not do this! Or SPI won't work as intended, or even at all.
spi.open(0,0)
spi.mode = 3

# Read the Device ID (should be xe5)
id = spi.xfer2([128,0])
print 'Device ID (Should be 0xe5):\n'+str(hex(id[1])) + '\n'

# Read the offsets
xoffset = spi.xfer2([30 | 128,0])
yoffset = spi.xfer2([31 | 128,0])
zoffset = spi.xfer2([32 | 128,0])
accres = 2
accrate = 13
print 'Offsets: '
print xoffset[1]
print yoffset[1]
# print str(zoffset[1]) + "\n\nRead the ADXL345 every half second:"

# Initialize the ADXL345
def initadxl345():
    # Enter power saving state
    spi.xfer2([45, 0])
    # Set data rate to 100 Hz. 15=3200, 14=1600, 13=800, 12=400, 11=200, 10=100 etc.
    spi.xfer2([44, accrate])

    # Enable full range (10 bits resolution) and +/- 16g 4 LSB
    spi.xfer2([49, accres])

    # Enable measurement
    spi.xfer2([45, 8])

# Read the ADXL x-y-z axia
def readadxl345():
    rx = spi.xfer2([242,0,0,0,0,0,0])

    #
    out = [rx[1] | (rx[2] << 8),rx[3] | (rx[4] << 8),rx[5] | (rx[6] << 8)]
    # Format x-axis
    if (out[0] & (1<<16 - 1 )):
        out[0] = out[0] - (1<<16)
#   out[0] = out[0] * 0.004 * 9.82
    # Format y-axis
    if (out[1] & (1<<16 - 1 )):
        out[1] = out[1] - (1<<16)
#   out[1] = out[1] * 0.004 * 9.82
    # Format z-axis
    if (out[2] & (1<<16 - 1 )):
        out[2] = out[2] - (1<<16)
#   out[2] = out[2] * 0.004 * 9.82

    return out

# Initialize the ADXL345 accelerometer
initadxl345()

# Read the ADXL345 every half second
timetosend = 60
while(1):
    with open('/proc/uptime','r') as f: # get uptime
        uptime_start = float(f.readline().split()[0])
    uptime_last = uptime_start
    active_file_first = "S3-" + str(pow(2,accrate)*25/256) + "hz10bit" + str(accres) + 'g' + str(datetime.datetime.utcnow().strftime('%y%m%d%H%M')) $
    active_file = active_file_first.replace(":", ".")
    wStream = open('/var/log/sensor/' + active_file,'wb')
    finalcount = 0
    print "Creating " + active_file
    while uptime_last < uptime_start + timetosend:
        finalcount += 1
        time1 = str(datetime.datetime.now().strftime('%S.%f'))
        time2 = str(datetime.datetime.now().strftime('%M'))
        time3 = str(datetime.datetime.now().strftime('%H'))
        time4 = str(datetime.datetime.now().strftime('%d'))
        time5 = str(datetime.datetime.now().strftime('%m'))
        time6 = str(datetime.datetime.now().strftime('%Y'))
        axia = readadxl345()
        wStream.write(str(round(float(axia[0])/1024,3))+','+str(round(float(axia[1])/1024,3))+','+str(round(float(axia[2])/1024,3))+','+time1+','+ti$
    # Print the reading
    # print axia[0]
    # print axia[1]
    # print str(axia[2]) + '\n'
    # elapsed = time.clock()
    # current = 0
    # while(current < timeout):
    #   current = time.clock() - elapsed
        with open('/proc/uptime', 'r') as f:
                uptime_last = float(f.readline().split()[0])
    wStream.close()

def doftp(the_active_file):
    session = ftplib.FTP('192.0.3.6','sensor3','L!ghtSp33d')
    session.cwd("//datalogger//")
    file = open('/var/log/sensor/' + active_file, 'rb')   # file to send
    session.storbinary('STOR' + active_file, file)        # send the file
    file.close()
    session.quit

My two other Raspberry Pi's show the following when I run the script:

Device ID (Should be 0xe5):

0xe5

Offsets:

This is supposed to be the same for my 3rd Raspberry Pi regardless of how the accelerometer is positioned before I run the script. However for some reason I get an output like this with my new Raspberry Pi:

Device ID (Should be 0xe5):

0x1

Offsets:

Sometimes it shows a complete different Device ID and offset.

All 3 Raspberry Pi have the exact same in both /etc/modules and /boot/config.txt.

When I run ls /dev/*spi* on both I get /dev/spidev0.0 /dev/spidev0.1 for all 3 Raspberry Pi's.

After exchanging MicroSD cards between the Raspberry Pi's it became clear that the issue has nothing to do with the hardware. It comes down to the software.

Does anyone in here have an idea of how I fix this issue? The fact that it isn't showing proper Device ID and offsets just makes the data I collect messed up and useless.

来源：https://stackoverflow.com/questions/48321492/adxl345-device-id-and-offset-being-wrong-raspberry-pi

标签

python

raspberry-pi

accelerometer

offset

deviceid