[En-Nut-Discussion] Using USART to Rx from PC Keyboard

Dave Smart SmartFamily at mchsi.com
Mon Dec 16 14:48:54 CET 2002


> 1. I already got a more advanced UART driver, supporting
XONOFF, parity etc. No HW handshake yet, but with all
the other standard stuff. No USART support so far.

Perhaps there's some convergence path here. Can you advance this to me?

> 2. As far as I remember from those old days with IBM
mainframes, synchronous operation is not connected to
a baudrate. Either one side or any independent part
generates the clock. This clock is then passed on a
specific line or somehow combined (NRZ etc) with the
data stream on the sender's side and extracted at the
receiver (PLL etc.).

Way down in my note, I indicated that I was using XCK as the clock/strobe
for the PC keyboard data into the USART1. So, I think I had this signal
taken into account.

> I can also remember having seen a PC keyboard interface
in the user project area of avrfreaks.

Yes, this was where I started, and following the sample, it was taking a
direct ISR for the keyboard clock line, and then sampling the data in the
ISR. Unfortunately, this was what spawned my note from Friday, looking into
the ISR blockage time. This was not a solution for the Ethernut environment.
Early Saturday was when I discovered the S in USART was there...

Any other thoughts from one or all?
Dave Smart

More information about the En-Nut-Discussion mailing list