SIM808 GSM/GPRS/GPS UART mini Modem, the latest addition of rhydolabz ,helps you with wireless connectivity for your project using TTL UART interface. It is a complete Quad-Band GSM/GPRS module that works on frequencies 850/ 900/ 1800/ 1900 MHz which combines GPS technology for satellite navigation. The compact design which integrated GPRS and GPS in a SMT package will significantly save both time and costs for customers to develop GPS enabled applications.

The Modem is manufactured with Automatic Pick and place machine with high quality standard. The Modem is coming with selectable interfacing voltage,which allows you to connect 2V8 to 5V , including 3V3 microcontroller directly without any extra level conversion chips. This module supports HTTP and TCP/IP protocol. It is suitable for SMS,voice,GPS,bluetooth,as well as data transfer application in M2M interface.It provide ultra low power consumption in sleep mode and integrated with charging circuit for Li-Ion battery,that make it get a super long standby time and convenient for projects.

Features of SIM808 UART Module

  •  High Quality Product (Not hobby grade)
  • Quad-band 850/900/1800/1900MHz
  • Make and receive voice calls, Send and receive SMS messages
  • Send and receive GPRS data (TCP/IP, HTTP, etc.)
  • Configurable Baud rate (9600-115200, factory default value: 9600)
  • AT command interface
  • Input voltage: 3.7V (Power through LIPO battery)
  • Onboard SMA connector for GSM.
  • Onboard  UFL connector for GPS.
  • Option for audio interface
  • Provision for firmware updation.
  • Onboard charging control for Li-Ion battery.
  • Quad-band 850/900/1800/1900MHz
  • GPRS multi-slot class 12/10
  • GPRS mobile station class B
  • Compliant to GSM phase 2/2+ – Class 4 (2 W @ 850/900MHz) – Class 1 (1 W @ 1800/1900MHz)
  • Dimensions: 24*24*2.6mm
  • Control via AT commands (3GPP TS 27.007, 27.005 and SIMCOM enhanced AT Commands)
  • Voltage range 3.4 ~ 4.2V
  • Low power consumption
  • Operation temperature:-40℃ ~+85℃
Pin out of SIM808

Pin Details



Getting Started

  • Insert an unlocked Micro Sim card to SIM card holder. 8 pin holder for Micro SIM card is provided on the modem.
  • Connect GSM antenna on Modem.
  • Connect Serial cable to modem.
  • Give the power supply with Li-Ion battery in between 3.7V to 4.2V through the power jack provided.
  • Default factory baud rate is 9600.
  • When the modem is successfully powered-up, the Red LED on the modem (PWR) will be ON, the STS LED(GREEN) will light after 1-2 seconds and the NET LED(BLUE) will blink every second. After the Modem registers in the network (takes between 10-60 seconds), this LED will blink in step of 3 seconds.
LED Status Description

The Network LED indicates the various status of GSM module eg. Power on, Network registration & GPRS connectivity. When the modem is powered up, this NETWORK LED will blink every second. After the Modem registers in the network (takes between 10-60 seconds), this LED will blink in step of 3 seconds. At this stage you can start using Modem for your application,showing that modem is registered with the network.

How to test

Connection Diagram

Connections should be like below :

  • TX(modem)-RX(converter TTL)
  •  RX(modem)-TX(converter TTL)
  •  VIO(Modem)-PWR(converter)
  •  Make ground (GND-GND)common.gistered with the network.
Check your GSM/GPRS Modem Using  Hyperterminal in PC:
  • You need RS232 – TTL (5V) Converter or FTDI Basic Breakout – 5V for making a connection between GSM/GPRS SIM808 UART mini modem and PC.
  • Firstly install a virtual serial port loading on the computer FT232RL drivers. Once the drivers are installed, connect the modem with converter.
  • Before making connection with the system you should power the modem with Li-Ion battery and ground should be common for both modem and converter.
  • After connecting the converter check the port number in the device manager of your PC.
  • Power the modem.
  • We are using Hyper terminal software ,Open the software and enter the name and press OK button.

  • Select the port as seen in the device manager Press ‘OK’ button and set the baudrate as 9600. Click on OK button.

  • Now let’s try to check our Modem with AT commands for that we need to send following AT commands to Modem as shown  below.

  •  The above shown command :AT command (followed by enter) after “OK” response, this signifies that our Modem is working properly.ATE0 command (followed by enter) is being sent to stop the echo. AT+CREG? (followed by enter) is being used to check whether the SIM got registered or not.
Sending a Text message from PC using AT commands 

  • The AT+CMGF=1 command (followed by enter) sets the GSM Modem in SMS text mode.
  • AT+CMGS=<number>followed by enter gives<CR><write message><Ctrl+z>
    <CR> represents the carriage return character.<Ctrl+z>When you finish entering the SMS message body, you have to enter the <Ctrl+z> character to mark the end of the SMS message body.
  • +CMGS: x with OK response; where x = “current number of sent SMS message
Receiving Text message in modem and display it in Hyper terminal.

Now we are going to see how a message is received using Rhydolabz GSM/GPRS/GPS SIM808 UART mini modem. For receiving message we need to first send related AT commands to initialize the modem.

  • AT+CNMI=2,1,0,0,0 command (followed by enter) set the modem to indicate received messages with +CMTI response indicates that new message has been received and shows location number of last received message  in above figure it is shown by number ’19′.
  • AT+CMGR=<index> :<index>integer type; value in the range of location numbers supported by the associated memory and gives +CMGR response which includes status i.e “REC UNREAD” Received unread messages,Sender’s number,date,time and received message.
Receiving a voice call from Modem using AT Commands
  • For receiving call we need headset,connector jack and modem.
  • Headset is connected in the connector jack of GSM Modem.
  • For receiving a call  firstly we need to send some AT commands as shown below.

  • Loudspeaker Volume Level

    0..max – the value of max can be read by issuing the Test command
    For example:
    AT+CLVL=100 -Command is used to select the volume of the internal loudspeaker audio
  • RING indicates incoming call.
  • For Attending call we are using ATA command (followed by enter) gives “OK” response when call is connected.
  • For Disconnecting call we are using ATH command  (followed by enter) gives “OK” response when call is disconnected.

Note: If you are interfacing with 5V level MCU you want to interface the VIO pin to 5V and if you are interfacing with 3.3V level MCU you want to interface the VIO pin to 3.3V

Receiving GPS location from Modem using AT Commands

  • For GPS power control (ON/OFF)we are using AT+CGPSPWR=1 command (followed by enter) gives “OK” response when GPS is ON.
  • AT+CGPSSTATUS is used to Read the GPS fix status . AT+CGPSSTATUS? command(followed by enter) gives” +CGPSSTATUS: Location 3D Fix” response when GPS has fixed with 3D status
  •  AT+ CGPSOUT is used to Read GPS information. AT+ CGPSOUT=255command (followed by enter )gives GPS NMEA data output .255 will allow all NMEA data output from Debug UART.

Test with PIC16F877A

  • Connect  the RX pin of MCU to TX pin of modem and TX pin of MCU to RX pin of modem. VIO to +5V and GND to GND.
    Sending SMS using PIC16F877A

Test with ARDUINO

  • Connect  the RX pin of MCU to TX pin of modem and TX pin of MCU to RX pin of modem. V-INT to +5V and GND to GND.
Sending SMS using Arduino

  How to buy


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