I have problem while interfacing GM862 with microcontroller

Wireless & IoT
1

hello

I have problem while interfacing GM862 with microcontroller so i designed a circuit and now given to design artwork of PCB.

Now i want conform whether this design is work properly or Not.

Project Title : Mihir Enterprises Vehicle Tracking Systems

Vehicle tracking system (VTS) it is a system allows user to know the location of their vehicle on the defined map at any time. The system is based on Global positioning system - a satellite based navigation system.

This system consists of two blocks:

A. Hardware units.

B. Front end software.

A. Hardware units:

It consists of two units in which vehicle unit is placed in a vehicle to get the position of vehicle from satellite and control unit is placed near computer from where vehicle is monitored.

  1. Vehicle Unit

  2. Control unit

Vehicle unit:

Function of this unit is take current position of vehicle and give that position to the control unit.

This unit consists of GPS module, GSM module and Microcontroller.

GPS (Global positioning system) receiver is used to get the position of the vehicle from the satellite in the form of Latitude, Longitude and time.

GSM (Global system for mobile communication) module is used to transmit data through SMS (Short messaging services) network to the control unit.

Microcontroller is used to control both GPS receiver and GSM module, it will take data from GPS receiver and will give it to GSM module.

Control unit:

Function of this is take data from transmitted by vehicle unit and give it to computer through serial port.

Control unit consists of GSM module and Microcontroller.

GSM (Global system for mobile communication) module is used to receive data

through a mobile network.

Microcontroller is used to control GSM module, and it will take data from GSM module and it will give it to computer through serial port.

B. Front end software:

Vehicle tracking system front end Software is already completed in Microsoft visual Basic 6.0 application software provided by windows.

In this program it will take data from serial port and display it on Map on the computer screen.

Vehicle unit required components are GPS receiver, GSM module and Microcontroller.

Selection of Microcontroller:

We have seen number of micrcontrollers and then depending on system requirements, availability, price, and possible for system updating Silicon Laboratories Microcontroller is selected.

Minimum requirements are:

Two serial UART

More than 1Kbye data memory

More than 16Kbyte program memory

If possible 4 channel in built ADC

Features of selected 8 bit Microcontroller Si Lab C8051F020:

12 bit and 10 bit SAR ADC

Two 12 bit DAC

4Kbytes + 256 bytes Internal RAM (data memory)

64 Kbytes program memory and EEPROM

2 UART

100 pin thin quad flatpack (TQFP)

GSM module:

Telit GM862-GSM

GSM module with sim card holder

2*25 pin SMD connector

GPS receiver module:

Fastrax uTracker 02 rev C

2*5 pin connector

Two serial UART

Power supply 180mW @3.0V

Required Level Translator IC’s :

ICL 3207CA

ICL 3241CA

To interface GSM module with microcontroller it needs level translator because, microcontroller works on TTL logic levels and GSM modules works on CMOS logic levels. To have communication between TTL logic and CMOS logic. we are using RS 232 level translators with ICL 3207CA with 5 transmitters, 3 receivers and ICL 3241CA has 3 transmitters, 5 receivers.

GSM module works on +3.8V whose interface signal is given to ICL3207CA with a +3.8V supply ICL3207CA RS232 output is given to RS232 input of ICL3241CA and ICL3241CA TTL output is given to Microcontroller whose power supply is +3.0V.

Is this interface will work properly. ?

Power supply circuitry is the most important part in the project design and it strongly reflect on the product’s overall performances. For RF transmission GSM module takes 2A current. Therefor power supply has to be designed in order to withstand with these peak currents. So we are using 500Khz step-down switching regulator LT1374CR which gives output voltage 3.8V, 2A.

GPS module and Microcontroller requires 3.0V, 200mA therefor we are using linear regulator LT1763CS-3 which gives output voltage 3.0,500mA.

Regards,

Sachin Gole.