sim808gpstracker

DIY cheap GPS motorbike/car tracker based on ATMEGA 328P (arduino uno chip) and SIM808 module from China (includes GPS and GNSS function). The total cost is below 20USD ( as in 2019 ) and positioning accuracy is ~1-20 meters ( tested in Europe location). Accoriding to SIM7500 / SIM7600 modules (LTE CAT1 ) specification this source code also may work on these boards (except usage of GPRS connectivity ).

You can find SIMCOM modules guides here : https://simcom.ee/documents/

The device when called by mobile phone polls info from GPS module (if can fix to sattelites - tries several minutes to fix) or when not available polls cell-id info from nearest 2G cell and using GPRS query Google servers for GPS location of that 2G cell. Collected location information is send back as text message to your phone as Google Map link. I have tried to keep the code as simple as possible and conserve battery power so functionality is rather limited... However...

There is also experimental version "main7.c"/"main8.c" which uses set of commands to control behavior of the tracking device using text messages. One of modes (MULTI) sends 5 times GPS location in 4-5 minutes interval upon receiving particular message. There is also GUARD option to alert in case vehicle has been stolen and is on the move...

The software can also be further customized to provide location in realtime to some HTTP POST /FTP server (see my other IoT project where I am doing it with SIM800L module which has same commands : https://www.youtube.com/watch?v=i4JgbwCktYQ , the code is here https://github.com/mcore1976/smartmetering) - it is up to you to expand the code, it will take you probably few hours to implement this feature... But REMEMBER - Using GPRS to send HTTP / TCP IP requires good power source for SIM808 board otherwise it will restart itself with "UNDERVOLTAGE WARNING"...

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BILL OF MATERIAL LIST (as for year 2019):

1. SIM808 based board BK-SIM808 (10-12 USD on Aliexpress )

• search for "www.and-global.com" boards BK-SIM808 or equivalent (you may try here http://and-global.en.alibaba.com/ )... https://cdn.instructables.com/ORIG/FAO/80RU/IXLALERK/FAO80RUIXLALERK.pdf) it may also work with boards SKU405361-SIM808 (see description below for source code options)

2. GPS (passive) antenna with IPEX / U.FL connector matching BK-SIM808 board - 2 USD

3. GSM antenna with IPEX / U.FL connector matching BK-SIM808 board - 1 USD

4. ATMEGA 328P (arduino uno) - 2 USD or ATMEGA328P based board : https://www.theengineeringprojects.com/2018/06/introduction-to-arduino-pro-mini.html

5. XTAL 8MHz - quartz crystal with 8 MHz frequency to ensure clock stability of ATMEGA and keep it synchronized with serial port of SIM808 module even when temperature changes (internal RC oscillator in ATMEGA is very unstable). Using XTAL is optional (compile scripts configure internal RC clock by default ) but i do RECOMMEND using XTAL due to poor internal clock of ATMEGA. This one costs 0.2USD

6. 2 x 22pF capacitor for XTAL - 0.2 USD

7. 3x 1N4007 (1 USD) - to convert 5V from powerbank to 3.3V for ATMEGA328P VCC ( only for BK-808 board and others that require TTL 3.3V logic)

8. 2x 1000uF / 16V capacitor ( 0.5 USD) - connect to VCC & GND of SIM808 board AND to existing 100uF (parallel) on the SIM808 board - usage of this capacitor depends on type of SIM808 board

9. 100nF (or some other in range 100nF-1uF) / 12V (or higher) capacitor (0.2 USD) - connect to VCC & GND of ATMEGA328P ( if not using "Arduino Pro Mini" board)

10. universal PCB, pins & connector (2 USD) or some wires with pins if you going to use boards like "Arduino Pro Mini" instead

11. USB Powerbank 5V to make it work...

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CONNECTIONS TO BE MADE :

1. SIM808 board RXD (BK-SIM808 pin R) to ATMEGA328 TXD PIN #3,
2. SIM808 board TXD (BK-SIM808 pin T) to ATMEGA328 RXD PIN #2
3. SIM808 board DTR (BK-SIM808 pin S : SLEEP PIN) to ATMEGA328 PC5 PIN #28
4. SIM808 board GND (BK-SIM808 pin G ) : to powerbank GND
5. SIM808 board VCC (BK-SIM808 pin V / PWRIN ) : to powerbank +5V VCC
6. SIM808 board PWRKEY (BK-SIM808 pin K - left unused - it is internally bound to GND, however when breaking this connection it can be used to switch on/off whole SIM808 board)

OPTIONAL) SIM808 RI/RING if available (No such pin on BK-SIM808 board) - to ATMEGA328P INT0 pin #4, and then you may experiment with ATMEGA POWERDOWN mode by uncommenting appropriate portion of the source code. I didn't have such board so I couldn't check this option.

7. Capacitor 1000uF between +5V and GND of powerbank (optional, most of them already has some huge capacitors)

8. put 3x 1N40007 diodes IN SERIAL between 5V VCC and ATMEGA328P VCC PIN #7 (only for BK808 board and others that use 3.3V TTL logic) - ATMEGA must be powered from ~3.3V to adopt TTL logic levels of outputs TXD/RXD of BK-SIM808 board

9. put 100nF capacitor between ATMEGA328P VCC pin #7 and ATMEGA328P GND pin #8 & PIN#22

10. connect GPS passive antenna and GSM antenna to appropriate IPEX / U.FL connectors of BK-SIM808 board. Probably it can work with active GPS antenna (but you would need to add another resistor for pullup antenna input to VCC - decribed here https://www.raviyp.com/embedded/205-sim808-gps-active-antenna-unable-to-acquire-fix-solution )

11. The AND-GLOBAL BK-SIM808 board I have used has TO SMALL electrolytic capacitor (mine had only 100uF). You have to solder/add another big capacitor (I have used 2200uF/10V, but it can be 1000uF/10V ) in parallel to make this board work correctly. Otherwise it will continously restart itself while trying to register to the 2G network.

12. Connect crystal 8MHz between pins 9 & 10 of ATMEGA 328p and add blocking capacitors 22pF between crystal pins and GND line. If you want to use crystal pleas modify "compileatmegaX" file by putting appropriate l-fuse value to avrdude command.

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SOURCE FILE OPTIONS :

You can find several boards with SIM808 on the market. Some of them have full pinout like GND,RXD,TXD,DTR,RING - but others can have only serial port exposed : GND, RXD, TXD. Some boards are using 3.3V TTL logic on serial port, but others use 5V TTL logic. You have to pay attention to all the details and consult the seller before buying development board.

Below there are two types of source files provided, first for BK-808 board (with PIN DTR/SLEEP and RXD/TXD) and second file for any SIM808 based board with only RXD,TXD pins.

------ for BK808 board or other WITH DTR/SLEEP pin --------

"main.c" (+ compilation script "compileatmega" Linux /"compileatmega.bat" Windows) - source file for SIM808 boards WITH DTR/SLEEP PIN exposed as BK-808 board. To use this file you will have to attach ATMEGA PC5 PIN #28 to SIM808 board DTR/SLEEP pin.

"main7.c" (+ compilation script "compileatmega7" Linux/"compileatmega7.bat" Windows) - EXPERIMENTAL VERSION - source file for SIM808 boards WITH DTR/SLEEP PIN exposed as BK-808 board. To use this file you will have to attach ATMEGA PC5 PIN #28 to SIM808 board DTR/SLEEP pin.

This version provides SMS (mobile texting) control of tracker behavior :

Command can be send in lower or upper letters. If command is correct it will be responded with appropriate text message confirmation.

• Command "ACTIVATE" stores the phone number of sender as allowed to MT call the device and get the current GPS/GSM position. Other calls will be ignored (security feature). Simply send a text message ACTIVATE to your simcard in GPS tracker to enable voice call answering with GPS position of the tracker to your phone number. This phone number will be stored in non volatile EPROM memory of ATMEGA328P chip so you need to send this command only once for your phonenumber. Only 1 phonenumber is stored and allowed to call.

• Command "MULTI" gives CONTINOUS MODE of positioning and sends 5 times GPS location in 3-4 minutes interval. Simply send a text message MULTI to your simcard in GPS tracker to receive five GPS positions in 20 minutes sequence.

• Command "SINGLE" gives single GPS/GSM positioning response. Simply send a text message SINGLE to your simcard in GPS tracker to receive single/current GPS position.

• Command "GUARD" has been added to notify caller of GPS position change using text message (~300-500 meter sensivity is hardcoded but can be changed in the program). "GUARD MODE" can be stopped by sending "STOP" message at least once (getting out of this mode is confirmed by text message) or ends up automatically after first detection of movement.

------- for other boards ( that do not have neither RING nor DTR pin exposed ) ------

"main2.c" (+ compilation script "compileatmega2" Linux / "compileatmega2.bat" Windows)
- source file for SIM808 boards WIHOUT DTR/SLEEP PIN exposed. To use this file you DO NOT connect ATMEGA PC5 pin to DTR SIM808.
Example of board wihout SLEEP/DTR is this module SKU405361-SIM808 http://files.banggood.com/2016/06/SKU405361-SIM808.rar . These boards are also sold here : https://www.electrodragon.com/product/sim808-dev-board-gsmgprsgps-replacing-sim908/

Also pay attention to type of TTL logic the board uses. They have to match on both sides - ATMEGA328P and SIM808 board - otherwise you may kill the SIM808 board. If you want to use board that has 5V TTL logic DO NOT put 1N4007 Diodes to ATMEGA328P. If you want to use 3.3V TTL logic on SKU405361-SIM808 (old type), you will probably need to connect 3.3V from ATMEGA VCC (after 3x 1N4007 Diode drop it from 5V) to VMCU PIN (if available) of SIM808 board to switch it to 3.3V mode. You need to check all the details in S