GSM and GPS Serial Communication Problem

for me it work absolutely fine..i had 2 option before..either to use another UC or to use UC wic can have 2 serial ports...

great.. really its a great circuit thanks for sharing. it might help many other users on forum. i have tagged i too..

Hey

Shezo can you please tell me why has the pin 4 of gsm modems db9 connector been connected to pin 2 of max 232?

Thats because you are Transmitting and Recieving at that DB9 connector for GSM..so u constantly giving it 5V from pin2..in case of GPS its not used because its only transmitting the data..

Do any body have software MAPOBJECTS 2 i need it urgently for Mapping

But what will happen if the data arrives from both the sources simultaneously ?

for that purpose there is Nand gate !! we cannot deal wid simultaneous data !!

GPS data is repeated every second so if you miss one packet doesnt matter it will come again next second but for GSM its the other case, when you send a command you get a reply in return, so its a lock step way of communication as soon as you get the response switch back to GPS uart.