invert TTL

[hani_a]

The UART i'm using outputs TTL. How do I get to output invert TTL?
is it enough to flip the data bits, or do i also have to invert the start and stop bits as well?

 

[Nigel Goodwin]

The UART i'm using outputs TTL. How do I get to output invert TTL?
is it enough to flip the data bits, or do i also have to invert the start and stop bits as well?

Generally (and certainly on PIC's) you have to provide a hardware inverter if using a UART - you can't invert it in software. You don't mention what you are using, or what you want to do, there may well be a software solution - but not usually when using a hardware UART.

 

[hani_a]

I'm using ATMEGA16. It provides me with code to transmit and receive data via the USART. Do you know why it's so difficult to find an invert-TTL device? I mean, I've been looking for an RS232 to invert TTL conversion device on the internet and I can't find anything.

Thanks!
Hani A.

 

[Nigel Goodwin]

I'm using ATMEGA16. It provides me with code to transmit and receive data via the USART. Do you know why it's so difficult to find an invert-TTL device? I mean, I've been looking for an RS232 to invert TTL conversion device on the internet and I can't find anything.

I'm not very sure what you are after, but a MAX232 converts between 5V and RS232 levels, AND inverts the signal. Are you wanting to feed to an RS232 port?. The hardware USART in a PIC is designed to be used with a MAX232 (or similar), presumably your processor is the same?.

 

[Exo]

Yes, It's the same on atmega's. Do a google search for MAX232. It should work, plenty of scematics on the net.