Multiple software USART's

Started by Milton Medicinteknik KB December 29, 2003
Hello all

The best way for a PIC to communicate with a device over RS 232 is to
use a USART equipped PIC. However, if volume is high and the PIC may be
a small one, it is cheaper to use a software USART.

This can be a timer interrupted testing process of a pin, shifting the
result (High/Low) through the status carry bit into a "RecByte"
register.

However - in my case I would like to test 5 pins in such way
(timerinterrupted as other processes are active as well) by
oversampling, and also send RS 232 data over 5 other pins. Thus, the
PIC becomes a "RS 232 hub"; for 9600 Baud.

My question to the group is: has anyone done this already ? Willing to
pay for code already up and running.

Kindly reply directly to Sven in Sweden





----- Original Message -----
From: "Milton Medicinteknik KB" <>
To: <>
Sent: Monday, December 29, 2003 6:17 PM
Subject: [piclist] Multiple software USART's > Hello all
>
> The best way for a PIC to communicate with a device over RS 232 is to
> use a USART equipped PIC. However, if volume is high and the PIC may be
> a small one, it is cheaper to use a software USART.
>
> This can be a timer interrupted testing process of a pin, shifting the
> result (High/Low) through the status carry bit into a "RecByte"
> register.
>
> However - in my case I would like to test 5 pins in such way
> (timerinterrupted as other processes are active as well) by
> oversampling, and also send RS 232 data over 5 other pins. Thus, the
> PIC becomes a "RS 232 hub"; for 9600 Baud.
>
> My question to the group is: has anyone done this already ? Willing to
> pay for code already up and running.

I developed a high-speed comms hub a couple of years ago using 2313 AVRs for
the UARTS and a PIC controlling the whole thing. The AVRs were interfaced to
the PIC via SPI. I think it handled four channels at 115k.

Leon
--
Leon Heller, G1HSM
Email:
My low-cost Philips LPC210x ARM development system:
http://webspace.webring.com/people/jl/leon_heller//lpc2104.html