Which microcontrollers have two serial ports ?

[sathish316]

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

 

[IanP]

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..

 

[bad]

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

 

[tgq]

Dual Serial Port

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

 

[mipedja]

Re: Dual Serial Port

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

 

[Ace-X]

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.