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Which microcontrollers have two serial ports ?

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sathish316

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Dual Serial Port

iM WORKING ON A project where i have to interface an 89c51 microcontroller with a GPS module and GSM mobile phone. Should i use a microcontroler with 2 serial ports? If so, which micros come with 2 serial ports. Do all micros with 3rd timer have a second serial port. What are the pins for the 2nd port?
In my case there is no need for simultaneous communication. Is it then possible to use a mC with a single port and use some ind of multiplexres, select lines transceivers etc. pls help
sathish
 

Re: Dual Serial Port

For this application there is no need for micro with 2 serial ports.
Most of GPSs doesn't even use RS-232 levels, instead they send out strings of 0-5V which can be directly connected to an AND or NAND gate(s) and by using additional pin from your micro you can select a device. Once you fetch desirable info from GPS switch to GSM. You have almost 1s before updated info from GPS is available..
 

Re: Dual Serial Port

It depends from levels ttl or RS232 !
1. U can install the controller with two ports like Cygnal ( www.cygnal.com)

2. Implement it on any pin by software ( usaly u do need to transmit back to GPS module ? u need onle to read GPS data)

3. Install some kind of switches like MAX4544 and periodicaly comutate yhe needed device to the one port of yours controller
 

Dual Serial Port

you can use the RS232 built-in port and take software RS232 functions for the second one
 

Re: Dual Serial Port

Cypress PSoC microcontroller can have more hardware serial ports
but it is not 8051based...
 

Dual Serial Port

I think, the cheapes solution would be ATMEGA162 (4-5$).

Also, you can consider MAX3100 - this is SPI<->UART bridge. Most of uC have SPI port in addition to 1 UART, so it could be solution.

For dual port cheap 8051 you should search Philips. They have couple uC in 10$ range.
 

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