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
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This is not answerable unless you explain how you connected everything together. For instance, are you sure your SIM800A is powered? – Dmitry Grigoryev 15 hours ago
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yes I am using 12v-2A power adapter to sim800a and without making any connection to my pi zero it’s network led should blink , SIM is working in cellphone fine. If led is not blinking then there is no point in checking it through pi zero – M.Shah 8 hours ago
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@M.Shah, Ah, let me see. (1) Last question first. SIM800A is an old, but matured product. As such, it is a very good tool to learn, especially to build a solid background, before moving to 5G (coming next year to my city!). It is popular, therefore you can find forum discussions of user problems etc. Even if you have not already bought the thing, I would encourage you NEVER GIVE UP!!! – tlfong01 32 mins ago
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@M.Shah, your following comment is not very clear, “… I am able to turn on the UART on pi zero and connect it over usb cable through ssh”. WARNING: SIM800 USB socket is for firmware upgrade and debugging, NOT for normal operation using AT commends etc. As you have already set up RpiZ USB (to serial UART adapter/cable, I assume) So perhaps we can start and focus to the serial AT command thing first. I am drafting an answer for newbies. Let me know if there is anything you could not follow, and I will try to explain in more details. – tlfong01 25 mins ago
Question
How to use RpiZ USB to serial adapter/cable to connect to SIM800A, and starting talking AT?
Answer
(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! 🙂
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References
(1) SIM800A Hardware Designer Guide V1.02 (English) – Shanghai SimCom Wireless Solutions 2016jun30
(2) SIM800A Hardware Designer Guide V1.02 (Simplified Chinese) – Shanghai SimCom Wireless Solutions 2016
(3) LinkWare Pilot (3GL, 3G/HSPA, PPP/CDC-ECM/CDC-NCM)
(4) LinkWare Pilot (3GL, 3G/HSPA) Forum Discussion
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Appendices
Appendix A – SIM800A Hardware Design Guide V1.02 (English) – Shanghai SimCom Wireless Solutions 2016jun30
Features
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.
Hardware interfaces
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
Programmable GPIO
Two PWM output
One ADC input
Bluetooth antenna interface
GSM antenna interface
Communication Protocol
UART, TCP/IP, extended TCP/IP AT commands
Frequency bands
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+
GPRS connectivity
Multi-slot class 12 (default) Multi-slot class 1~12 (option)
Data GPRS
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)
SMS
MT, MO, CB, Text and PDU mode
SMS storage: SIM card
Serial port
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
USB
For debugging and upgrading firmware
Appendix B – LinkWare Pilot ((3GL, 3G/HSPA, PPP/CDC-ECM/CDC-NCM)
Features
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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