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Sharing 8051 UART for two applications

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vamanan

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Friends,
I want to use the UART of 8051 for two different applications one using the UART at one time. Is it possible to switch the TXD and RXD pins to the particular application when there is a need. If possible please tell me which component to use.
Thanx in advance.
Regards,
Vamanan
 

Without going into details I don't think you can do it ..
But, don't worry, there is another option ..
You can implement second UART in software and use any selected general I/O pins as Tx2 and Rx2 ..
Here is an example:
**broken link removed**
The following program contains routines that will allow an 8xC751 or 8xC752 to implement a software UART that can send and receive serial data simultaneously.
Click to expand...
This subroutine can be implemented on any 8051-derivative ..

Regards,
IamP

All of the above applies to situation when you would like to simultanously operate both applications - 2 UARTS - otherwise a couple of gates/switches + additional control pin to select application as suggested below should do ..
 

With cmos bilateral switches(4066) or 3-state buffers you can connect TXD and RXD pins to your appropriate application. This requires 2 control signals.
 

Are You Reffering To Software Or Hardware Application ?
 

Hi,
if you whant to had two RS connectors, and switch uC USART betwen them you can do this, my suggestion si to switch standard logic level and put two MAX232 ot similar convertor to bipoliar output.
 

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