Receiving No Data

[musch711]

Hi,

I’m trying to connect the Berry GPS-IMU to a Raspberry Pi 4 using the QWIIC connector.  The led on the GPS is lit green, but I’m receiving no data on serial0 (using cat /dev/serial0 hangs).  I’ve included some diagnostic output below.  I’d appreciate any suggestions or advice.

Thanks,

Steven

pi@raspberrypi:~ $ dmesg | grep tty
[ 0.000000] Kernel command line: coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 video=HDMI-A-1:1920x1080M@60,margin_left=48,margin_right=48,margin_top=48,margin_bottom=48 smsc95xx.macaddr=DC:A6:32:D5:5D:CE vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 console=tty1 root=/dev/mmcblk0p7 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[ 0.001057] printk: console [tty1] enabled
[ 1.238296] fe201000.serial: ttyAMA0 at MMIO 0xfe201000 (irq = 29, base_baud = 0) is a PL011 rev2
[ 1.244976] fe215040.serial: ttyS0 at MMIO 0x0 (irq = 30, base_baud = 62500000) is a 16550

[Mark Williams]

You will need to have the BerryGPS-IMU sitting ontop of the Raspberry Pi GPIO to get access to the GPS data via serial

Mark --OzzMaker.com --

[musch711]

Hi Mark,

I thought according to this, the QWIIC connector could serve as an alternative instead of mounting the IMU directly on top and soldering the connection.  Is that not accurate?

Thanks,

Steven

[Mark Williams]

Sorry if it wasn’t clear.  ill make sure that page gets updated.

If you connect via QWIIC connector only, you would only be able to access the GPS module via i2c (you would need to solder a couple of jumpers on the back to enable this function).   This means you would not be able to use GPSD as GSPD relies on serial.  We are trying to come up with a way to make it work with GPSD via i2c.

You can however, get lon,lat, speed, etc.. via i2c using

 
Here is some python code I have been playing around with;

import time
import json
import smbus
import logging 
BUS = None
address = 0x42
gpsReadInterval = 0.1
LOG = logging.getLogger()
GPSDAT = {
    'strType': None,
    'fixTime': None,
    'lat': None,
    'latDir': None,
    'lon': None,
    'lonDir': None,
    'fixQual': None,
    'numSat': None,
    'horDil': None,
    'alt': None,
    'altUnit': None,
    'galt': None,
    'galtUnit': None,
    'DPGS_updt': None,
    'DPGS_ID': None
}
def connectBus():
    global BUS
    BUS = smbus.SMBus(1)
def parseResponse(gpsLine):
    global lastLocation
    gpsChars = ''.join(chr(c) for c in gpsLine)
    if "*" not in gpsChars:
        return False
    gpsStr, chkSum = gpsChars.split('*')    
    gpsComponents = gpsStr.split(',')
    gpsStart = gpsComponents[0]
    if (gpsStart == "$GNGGA"):
        chkVal = 0
        for ch in gpsStr[1:]: # Remove the $
            chkVal ^= ord(ch)
        if (chkVal == int(chkSum, 16)):
            '''for i, k in enumerate(
                ['strType', 'fixTime', 
                'lat', 'latDir', 'lon', 'lonDir',
                'fixQual', 'numSat', 'horDil', 
                'alt', 'altUnit', 'galt', 'galtUnit',
                'DPGS_updt', 'DPGS_ID']):
                GPSDAT[k] = gpsComponents'''
            print gpsChars
            #print json.dumps(GPSDAT, indent=2)
def readGPS():
    c = None
    response = []
    try:
        while True: # Newline, or bad char.
            c = BUS.read_byte(address)
            if c == 255:
                return False
            elif c == 10:
                break
            else:
                response.append(c)
        parseResponse(response)
    except IOError:
        time.sleep(0.5)
        connectBus()
    except Exception, e:
        print e
        LOG.error(e)
connectBus()
while True:
    readGPS()
    time.sleep(gpsReadInterval)

Mark --OzzMaker.com --

[musch711]

Hi Mark,

Thanks for the follow up with code sample!  I enabled i2c and was able to get some readings from it; however, given what you mentioned about additional soldering for GPS, I’m currently limited to the accelerometer.  I used the following code: https://github.com/ozzmaker/BerryIMU/blob/master/python-BerryIMU-gryo-accel-compass/berryIMU-simple.py to get the reading.

Thank you for your help and I’ll follow up if I have additional questions!

-Steven

[vovacooper]

Hi Mark,
i got the V4 GPS-IMU module, trying to connect it to Jetson via qwiic (i2c), all working well but the GPS :(.

i saw that u wrote “If you connect via QWIIC connector only, you would only be able to access the GPS module via i2c (you would need to solder a couple of jumpers on the back to enable this function)…”

Unfortunately i cant find any place that specifies which jumpers i need to solder.

Can u please explain which jumpers i need to solder for the GPS to start working via I2C?

Thanks

[Mark Williams]

Hi, we are in the middle of writing up a guide on this, it should be posted soon.
But, in summary.. its JP7& JP8

Mark --OzzMaker.com --

[vovacooper]

Sorry to bother you but its very frustrating that you just writing a guid on a product i already have…

It looks like the JP7 and JP8 is has a connection already (without soldering)…
Do i need to there it off?

do i need to connect JP7 to JP8?

What should i do to make the GPS work with I2C?

thanks

[vovacooper]

found it 🙂

it was JP10 + JP11 and not JP7 + JP8

🙁

 

[richardp]

You are right!  I am so sorry.. not sure what I was looking at 🙁

Richard --OzzMaker.com --

[Author]

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