Connect to the Internet via PPP with Sixfab GSM/GPRS Shield on Raspberry Pi

14 Aug 2018

Sixfab’s Raspberry Pi GSM/GPRS Shield is a nice little IoT modem to connect the Pi to the internet in remote locations via a 2G mobile network.

Serial Port Configuration

1. In /boot/cmdline.txt remove the console=serial0,115200 part.
2. Add this lines to /boot/config.txt:

   enable_uart=1
   dtoverlay=pi3-disable-bt
   

3. Disable the serial-getty service:

   systemctl stop serial-getty@ttyAMA0.service
   systemctl disable serial-getty@ttyAMA0.service
   

4. Power-off the Pi.
5. Connect the Sixfab GSM/GPRS Shield to the Raspberry Pi’s GPIO pins.
6. Make sure the physical switch on the Shield is set to “Pi” (not USB!)
7. Power-on the Pi.

PPP

1. Install the ppp package:

   apt-get update
   apt-get install -y ppp
   

2. Create directories:

   mkdir -p /etc/chatscripts /etc/ppp/peers
   

3. Create /etc/chatscripts/quectel-chat-connect file:

   ABORT "BUSY"
   ABORT "NO CARRIER"
   ABORT "NO DIALTONE"
   ABORT "ERROR"
   ABORT "NO ANSWER"
   TIMEOUT 30
   "" AT
   OK ATE0
   OK ATI;+CSUB;+CSQ;+CPIN?;+COPS?;+CGREG?;&D2
   OK AT+CGDCONT=1,"IP","\T",,0,0
   OK ATD*99#
   CONNECT
   

4. Create /etc/chatscripts/quectel-chat-disconnect file:

   ABORT "ERROR"
   ABORT "NO DIALTONE"
   SAY "\nSending break to the modem\n"
   "" +++
   "" +++
   "" +++
   SAY "\nGoodbye!\n"
   

5. Create /etc/ppp/peers/gprs

   /dev/ttyAMA0 115200
   connect 'chat -s -v -f /etc/chatscripts/quectel-chat-connect -T <$APN>'
   disconnect 'chat -s -v -f /etc/chatscripts/quectel-chat-disconnect'
   hide-password
   noauth
   debug
   defaultroute
   noipdefault
   novj
   novjccomp
   noccp
   ipcp-accept-local
   ipcp-accept-remote
   local
   lock
   modem
   dump
   nodetach
   nocrtscts
   remotename 3gppp
   ipparam 3gppp
   ipcp-max-failure 30
   usepeerdns
   

Usage

1. To power-up the Shield using the GPIO pins, use this Python script:

   #!/usr/bin/env python
   
   import RPi.GPIO as GPIO
   import time
   GPIO.setmode(GPIO.BCM)
   GPIO.setup(26, GPIO.OUT)
   GPIO.output(26, True)
   time.sleep(2)
   GPIO.output(26, False)
   GPIO.cleanup()
   

2. Initiate GPRS call to connect to the internet:

   pppd call gprs &
   

Optional

• Make the PPP connection the default route (optional):

  route del default
  route add default dev ppp0
  

• Disconnect the PPP connection:

  kill -9 `pidof pppd`
  

1. https://sixfab.com/sending-sms-with-sixfab-gsmgprs-shield/
2. https://sixfab.com/updated-tutorial-2-make-a-ppp-internet-connection-with-sixfab-gprs-shield-on-raspberry-pi/