pic telemetry system

[Ioannis]

For the soft uart case. I seldom use the software choice, but if I do, I make sure that the first thing the program does is to issue a high on the serial port (or low, depends of the way it drives the line).

Then a pause of 1sec and the serial port is initialized to the idle state. Otherwise, it sees an invalid state and the first at least character is messed up.

Ioannis

[comwarrior]

Morning ioannis,

thats interesting... i completely understand where your coming from... i'm wondering if my trisb is too close (time wise) to my 'initialised' output line...

I'm going to sim some variations including setting the port to high or low and waiting...

Everything i've read on software UART indicates the fastes speed is 9600... can it not go any faster? 19200 would be handy...
i understand why it's speed limited, i'm just asking if it can? other than me programing a software uart myself...

Thanks

[Ioannis]

TRIS has nothing to do with this. Just give the serial port enough time to set idle. Normally one character (1/9600 x 10) is more than enough time for your terminal to disregard any "startup noise" from your PIC while powering up.

As for the speed,since it is soft UART, a faster PIC/Clock will drive your port fast. 19200 is no problem for a 20MHz clock.

Consider to use the harware UART though. It has also a 2 byte buffer and interrupt too. Even better choose a chip with 2 hardware usarts (some of the 18F series).

Ioannis