gnupic: Thread: 16F877 I/O

Hi,

I'm trying to implement serial rs232 communication for the PIC16F877 by
software instead of using the built-in UART (dedicated to other task). What
resources (links, lectures, source code, etc) would you recomend me for this
task.
Thank you in advance,
Gaston.



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.614 / Virus Database: 393 - Release Date: 05/03/2004

On Mon, 8 Mar 2004, Gaston G. Izaguirre wrote:

> Hi,
> 
> I'm trying to implement serial rs232 communication for the PIC16F877 by
> software instead of using the built-in UART (dedicated to other task). What
> resources (links, lectures, source code, etc) would you recomend me for this
> task.

I'd recommend dedicating TMR2. If you only need to transmit from the F877 
then you can program TMR2 to generate an interrupt equal to the time for a 
single bit. If you have to receive as well, then you're going to want to 
poll at least 3 times faster and use a majority weighting to determine the 
sampled bit. You may wish to search piclist.com (before you do this, 
you'll have to turn on cookies in your browser...) for an example.

Scott

On 8 Mar 2004 at 10:47, Scott Dattalo wrote:

> On Mon, 8 Mar 2004, Gaston G. Izaguirre wrote:
> 
> > Hi,
> > 
> > I'm trying to implement serial rs232 communication for the PIC16F877 by
> > software instead of using the built-in UART (dedicated to other task). What
> > resources (links, lectures, source code, etc) would you recomend me for this
> > task.
> 
> I'd recommend dedicating TMR2. If you only need to transmit from the F877 
> then you can program TMR2 to generate an interrupt equal to the time for a 
> single bit. If you have to receive as well, then you're going to want to 
> poll at least 3 times faster and use a majority weighting to determine the 
> sampled bit. You may wish to search piclist.com (before you do this, 
> you'll have to turn on cookies in your browser...) for an example.
> 
> Scott
>
Maybe the program NONAME.A16 is useful to you. It is commented in German
however. Look for the item 'SERIELL'. It is developed as a bar code
reader. It is part of my software you can download at
http://fholzinger.com/Diplomarbeit.zip . 
To get the password you have to send me an extra email.

Franz

HI Franz Holzinger,

> > > I'm trying to implement serial rs232 communication for the PIC16F877 by
> > > software instead of using the built-in UART (dedicated to other task). What
> > > resources (links, lectures, source code, etc) would you recomend me for this
> > > task.
> > 
> > I'd recommend dedicating TMR2. If you only need to transmit from the F877 
> > then you can program TMR2 to generate an interrupt equal to the time for a 
> > single bit. If you have to receive as well, then you're going to want to 
> > poll at least 3 times faster and use a majority weighting to determine the 
> > sampled bit. You may wish to search piclist.com (before you do this, 
> > you'll have to turn on cookies in your browser...) for an example.
> > 
> Maybe the program NONAME.A16 is useful to you. 
> It is commented in German
> however. Look for the item 'SERIELL'. It is developed as a bar code
> reader. It is part of my software you can download at
> http://fholzinger.com/Diplomarbeit.zip . 
> To get the password you have to send me an extra email.

I want to simulate a mouse, which AFAIK transmits at 9600 Baud
 with 3 bytes for each action ?
The "interrupt equal to the time for a single bit" seems the best way.
The minimal PIC [which I guess is 16c84] should do it.
This whole 'updating PIC towards an ARM' seems as rediculous to
me as updating a wheel-barrow to a Ferari.
Wheelbarrows are marvelous for their application.

Thanks for any pointers/passwords. 
No I don't enable cookies !


== Chris Glur.

On -1 xxx -1 ####@####.#### wrote:

> I want to simulate a mouse, which AFAIK transmits at 9600 Baud
>  with 3 bytes for each action ?
> The "interrupt equal to the time for a single bit" seems the best way.
> The minimal PIC [which I guess is 16c84] should do it.
> This whole 'updating PIC towards an ARM' seems as rediculous to
> me as updating a wheel-barrow to a Ferari.
> Wheelbarrows are marvelous for their application.

If you're talking about a serial mouse, then maybe it is 9600. But those 
are very rare these days. If you're talking about PS/2 then it's not 9600 
baud. Instead, PS/2 is a clocked-serial, or bit-synchronous, protocol. I 
work for Synaptics and PS/2 is used by our TouchPads to communicate with a 
host. PS/2 has many, many idiosynchracies and the industry is trying to 
rid itself of it. However, in a commodity market, you can't beat the cost 
compared to a USB-type solution (even though everyone agrees USB is
technically superior).

If you want technical info, then check out Synaptics' web page:

http://www.synaptics.com/support/dev_support.cfm

and specifically:

http://www.synaptics.com/decaf/utilities/ps2-mux.PDF


Scott