Connect sim800 to Raspberry PI (RX, TX)

Question

I've been trying to connect my sim800L to my Raspberry pi 3 model B (rasbian) but without success... I'm at the very first step, and since I'm new to Raspberry pi, I don't understand very well how it works. Here is how I'm trying to connect it: After some research, I've found that I needed to add some things to the /boot/config.txt file in order to enable the UART, so I've added this : core_freq=250 enable_uart Edit : my version is My version is 4.4.50-v7+ so I don't need enable_uart After, I found out a code that matched what I'm trying to do, here it is: import serial import os, time # Enable Serial Communication port = serial.Serial('/dev/ttyS0', baudrate=9600, timeout=1) # Transmitting AT Commands to the Modem # 'rn' indicates the Enter key port.write('AT'+'rn') rcv = port.read(10) print rcv But nothing is working in the Python Shell, no matter if I'm using ttyS0 or Serial0, when I try the AT command, which is supposed to answer OK if the sim800L is successfully connected. I'm getting some basic error (after typing AT): >>> AT Traceback (most recent call last): File "", line 1, in AT NameError: name 'AT' is not defined How can I resolve this error?

user122570 · Answer

Please read manuals. There is no 'AT' + 'rn', use "ATr" instead. No need for New Line 'n', only Carriage Return 'r'. Also, before any other commands, SIM800 is by default working at 115200 baudrate, so "ATr" + "AT+IPR=9600r" or any other baudrate is a MUST been sent to it.

Answered by user122570 on September 15, 2020

Manu · Answer

Just yesterday I managed to make my assembly respond. Here are my steps:

Disable Serial Console
sudo raspi-config --> Interfaces --> Serial --> No to 1st prompt; Yes for the 2nd
Use "serial0" instead of "ttyAMA0" or "ttyS0"

*Edit: Appended working code

import serial
    import RPi.GPIO as GPIO
    import os, time
    GPIO.setmode(GPIO.BOARD)
    port = serial.Serial("/dev/serial0", baudrate=9600, timeout=1)
    port.flush()
    port.write('AT'+'rn')
    rcv = port.read(10)
    print rcv
    time.sleep(1)

joan · Answer

The circuit as shown will not work as there is no common voltage reference between the SIM and the Pi.

You need to connect a Pi ground to either the SIM ground or to the battery ground (-ve terminal).

Liam · Answer

that's probably the code you are looking for:

import serial
import RPi.GPIO as GPIO     
import os, time

GPIO.setmode(GPIO.BOARD)

# Enable Serial Communication
port = serial.Serial("/dev/ttyS0", baudrate=9600, timeout=1)

# Transmitting AT Commands to the Modem
# 'rn' indicates the Enter key

port.write('AT'+'rn')
rcv = port.read(10)
print rcv
time.sleep(1)

port.write('ATE0'+'rn')      # Disable the Echo
rcv = port.read(10)
print rcv
time.sleep(1)

port.write('AT+CMGF=1'+'rn')  # Select Message format as Text mode
rcv = port.read(10)
print rcv
time.sleep(1)

port.write('AT+CNMI=2,1,0,0,0'+'rn')   # New SMS Message Indications
rcv = port.read(10)
print rcv
time.sleep(1)

# Sending a message to a particular Number

port.write('AT+CMGS="XXXXXXXXXX"'+'rn')
rcv = port.read(10)
print rcv
time.sleep(1)

port.write('Hello User'+'rn')  # Message
rcv = port.read(10)
print rcv

port.write("x1A") # Enable to send SMS
for i in range(10):
    rcv = port.read(10)
    print rcv

for more information have a look at this page

Connect sim800 to Raspberry PI (RX, TX)

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