I am trying to send sms using RPI Add on v22 module and Raspberry-pi 3+.

I have mounted this module on top of Raspberry-pi.

When I use minicome using minicom -D /dev/ttyS0 -b 115200 -o

I get the terminal, but I can not type anything on that terminal. What's the problem there? My module is burnt?

The Module I use

My /boot/config.txt


My /boot/cmdline.txt

dwc_otg.lpm_enable=0 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait

My /lib/systemd/system/hciuart.service

After = dev-ttyS0.device

ExecStart = /usr/lib/hciattach /dev/ttyS0 bcm43xx 460800 noflow -

as given here.

My program is

import serial
import RPi.GPIO as GPIO
import os, time
port = serial.Serial("/dev/ttyS0", baudrate=9600, timeout=1)
rcv = port.read(10)
print rcv

In terminal I get nothing printed, at least AT command. If I change /dev/ttyS0 to /dev/ttyAMA1, AT command printed on terminal. But no ok coming from device.

Here they suggested to edit /etc/inittab, but I dont have any file there in my Pi.

I have separate 5V/2A power supply to the GSM module.

Added later by author: I have used minicom, sudo minicom -D /dev/ttyS0, but it has nothing

What am I missing here? I am new to these GSM modules. Any help would be greatly appreciated.

  • 1
    You should try communicating with it using minicom, screen, or miniterm.py (the last one is probably the easiest and would have been installed with py-serial), so that you know you have a working configuration. Once that's established you can try with your own code.
    – goldilocks
    Aug 30 '19 at 12:41
  • 1
    Edit new information into the question. Keep in mind many people will scan the question and leave if there is too much ambiguity for them to want to get entangled. They won't bother reading the comments.
    – goldilocks
    Aug 30 '19 at 13:05
  • 1
    I think you need to give a link to this "add-on".
    – joan
    Aug 30 '19 at 15:25
  • 1
    If that is designed to sit on the Pi you should not be swapping TX and RX. You should connect pin to pin.
    – joan
    Aug 30 '19 at 16:31
  • 1
    @Sachith, SIM800 Rpi Add On is a popular card. You can google many tutorials.
    – tlfong01
    Aug 31 '19 at 0:42

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