I am new to raspberry pi zero and I want to connect it with gsm module for gprs connectivity . I bought sim800a gsm module but its led not even blinking single time I am able to turn on the UART on pi zero and coonect it over usb cable through ssh . Can anyone help me out how to achieve what I want and also suggest a better gsm module for gprs if sim800a is not good enough
How to use RpiZ USB to serial adapter/cable to connect to SIM800A, and starting talking AT?
(1) Introduction and Functional Block Diagram
First thing first, let us look at the functional block diagram, and make sure we know which “function” we are messing around. It is吖good idea to start with the simplest thing first, in our case, UART. Forget for now the newbie scary things I2C, SPI! 🙂
(2) How can Rpi send AT serial commands to SIM800?
I read that SIM800 can talk with Rpi using serial AT commands. So perhaps we can start looking at the UART setup and any Hello World AT command shall we use.
(3) SIM800 Serial Communication Specification
Now I am read the manual to see how SIM800 serial looks like. It seems that SIM800 can do auto baudrate detect. In other words, if Rpi is set to No Parity, 1 stop bit (8N1) any speed, SIM800 should at power up, detect Rpi 9600 N81 “AT” command and responds with something like “OK” (See Ref 6).
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Dual-band GSM/GPRS module that works on frequencies EGSM 900MHz and DCS 1800MHz
GPRS multi-slot class 12/ class 10
GPRS coding schemes CS-1, CS-2, CS-3 and CS-4.
One UART port
One USB port for debugging and firmware upgrading
Audio channel which includes a microphone input and a receiver output
One SIM card interface
Support up to 4*5 Keypads
One display interface
One I2C master interface for peripheral management
Two PWM output
One ADC input
Bluetooth antenna interface
GSM antenna interface
UART, TCP/IP, extended TCP/IP AT commands
EGSM 900, DCS 1800
Can search the 4 frequency bands automatically.
Frequency bands can be set by AT command “AT+CBAND”.
GSM Phase 2/2+
Multi-slot class 12 (default) Multi-slot class 1~12 (option)
Downlink transfer: max. 85.6 kbps
Uplink transfer: max. 85.6 kbps
Coding scheme: CS-1, CS-2, CS-3 and CS-4
Integrate the TCP/IP protocol.
Support Packet Broadcast Control Channel (PBCCH)
MT, MO, CB, Text and PDU mode
SMS storage: SIM card
Full modem serial port
Can be used for AT commands or data stream
Support RTS/CTS hardware handshake
Comply with GSM 07.10 Multiplexer Protocol
Support auto baud detect from 1200 bps to 115,200bps
For debugging and upgrading firmware
The PiloT is a HAT compliant board which is compatible with all versions of Raspberry Pi with 40 pin header, including Pi 2,3 and Zero models.
Fully controllable with I/O pins, the PiloT can communicate with the Pi over USB or serial ports.
Two versions are available – the PiloT 3GL, which offers hexaband 3G/HSPA for global coverage, with fallback to EDGE/GPRS, and SiRF V GNSS technology, and the PiloT 4G-1,which is an LTE CAT-1 device with fallback to 2G for Europe.
The PiloT can be fully controlled from the Raspberry Pi, and can support data communication using either PPP or CDC-ECM (PiloT 3GL) or CDC-NCM (PiloT 4G-1). Scripts to automate communication setup are available. (Recommend use of USB ports for Pi 3 as the main serial port is used for Bluetooth / Wi-Fi communication)
The PiloT is currently compatible with the following devices: Rpi2/3, B/B+, RpiZ/ZW
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