Microchip PIC16F877A Microcontroller Features:-
High-Performance RISC CPU
- Operating speed: 20 MHz, 200 ns instruction cycle
- Operating voltage: 4.0-5.5V
- Industrial temperature range (-40° to +85°C)
- 15 Interrupt Sources
- 35 single-word instructions
- All single-cycle instructions except for program branches (two-cycle)
Special Microcontroller Features:
- Flash Memory: 14.3 Kbytes (8192 words)
- Data SRAM: 368 bytes
- Data EEPROM: 256 bytes
- Self-reprogrammable under software control
- Watchdog Timer with on-chip RC oscillator
- Power-saving Sleep mode
- Selectable oscillator options
The PIN diagram of PIC 16F877
Gobal system for mobile communication (GSM)
Definition - Global system for mobile communication is globally accepted standerd for digital cellular communication. GSM is the name of standardization group established in 1982 to create a common European mobile telephone standard that would formulate specifications for a pan-European mobile cellular radio system operating at 900 MHz.
The GSM standard is intended to address the problems of compatibility,especially with the development of digital radio technology.
- Frequency band-1850 to 1990 MHz
- Duplex distance-80 MHz(distance between uplink and downlink).
- Channel separation-200KHz(separation bet adjacent carrier frequncies).
- Tx rate-270kbps
- Access method-TDMA.
- Speech coder-Line Predictive Coding(LPC).
- DTMF,FAX group3,SMS,cell broadcast,voice mail,FAX mail.
- Call forwding,barring of outgoing n incoming calls,call hold,call waiting, multiparty service.
It is dual driver/receiver that includes a capacitive voltage generator to supply TIA/EIA-232-F voltage levels from single 5V supply.Each receiver converts EIA inputs to 5V TTL/CMOS levels.hese receivers have typical threshold of 1.3V.Driver does opposite action of receiver.