[SOLVED] Pin state on Tx/Rx pin while USART communication

[sgreen]

In case of serial communication(using ATmega32A) first I have to initialize USART and do code for serial Tx/Rx. In hardware,is Tx/Rx pin always in 5V or logic1?

 

[jayanth.devarayanadurga]

If it is a 5V device then Rx and Tx pins will toggle between 0V and 5V. If it is a 3.3V device then it toggles for 0V and 3.3V.

 

[zuisti]

In case of serial communication(using ATmega32A) first I have to initialize USART and do code for serial Tx/Rx. In hardware,is Tx/Rx pin always in 5V or logic1?

When we talking about a TTL level USART, then yes, the idle state of both (Rx and Tx) pins is high as usual; a MAX232 (if any) will be inverted them.

 

[sgreen]

When we talking about a TTL level USART, then yes, the idle state of both (Rx and Tx) pins is high as usual; a MAX232 (if any) will be inverted them.

My system sends data through USART every 10ms. And my Tx pin is always 5.07V. Is it possible? It will be better for me if you provide me article/link which shows transmission characteristics of usart Tx/ RX pin.

 

[jayanth.devarayanadurga]

If you send 10011000 then you get data comes out of the Tx pin like first the 0th bit comes out and 7th bit is the last to come out. Whenever logic zero is transmitted the Tx pin is internally grounded.

 

[sgreen]

If you send 10011000 then you get data comes out of the Tx pin like first the 0th bit comes out and 7th bit is the last to come out. Whenever logic zero is transmitted the Tx pin is internally grounded.

Sending speed is so first that I can't understand. Am I right? And for this reason always Multimetre result is 5V always.

 

[jayanth.devarayanadurga]

Maybe 10ms is fast. You need a Oscilloscope to see the data transmitting. Instead use a led indicator a blink it if transmission is successful or on the receiver side light an led if data is received.