[PIC]: 18f4550 UART TX/RX Inversion not working?

[andrew kelley]

Good day,

I have been trying to get my 18f4550 to invert TX data but it refuses to do
so.. I set TXCKP and cleared RXDTP, expecting no data to flow loopbacked
using the CDC serial example, but to my disappointment, I see echoed exact
data. I found errata for the A3 silicon, but I believe I have B3 silicon
chips, as the last two characters on the second line is B3.

Any hints?

Thanks much,
Andrew Kelley

[IVP]

Hi Andrew,

I had a few problems with the 4550 UART and found silicon bugs
in a couple of the register bits

Best you can do is twiddle with them in various combinations and
polarities to see what works

all the best

Joe

---
This email has been checked for viruses by AVG.
http://www.avg.com

[Forrest Christian (List Account)]

The safest way to tell the revision of a pic is to read the revision from
the chip itself. The first page of the errata discusses how to do this,
and how to interpret the value.

On Oct 16, 2017 10:38 PM, "andrew kelley" <***@gmail.com> wrote:

Good day,

I have been trying to get my 18f4550 to invert TX data but it refuses to do
so.. I set TXCKP and cleared RXDTP, expecting no data to flow loopbacked
using the CDC serial example, but to my disappointment, I see echoed exact
data. I found errata for the A3 silicon, but I believe I have B3 silicon
chips, as the last two characters on the second line is B3.

Any hints?

Thanks much,
Andrew Kelley
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[andrew kelley]

Thanks, I'll try that and post my results.. might well be the affected
revision.. they are /quite/ old. Like 2006.


On Tuesday, October 17, 2017, Forrest Christian (List Account) <

Post by Forrest Christian (List Account)
The safest way to tell the revision of a pic is to read the revision from
the chip itself. The first page of the errata discusses how to do this,
and how to interpret the value.
Good day,
I have been trying to get my 18f4550 to invert TX data but it refuses to do
so.. I set TXCKP and cleared RXDTP, expecting no data to flow loopbacked
using the CDC serial example, but to my disappointment, I see echoed exact
data. I found errata for the A3 silicon, but I believe I have B3 silicon
chips, as the last two characters on the second line is B3.

[andrew kelley]

Post by andrew kelley
Thanks, I'll try that and post my results.. might well be the affected
revision.. they are /quite/ old. Like 2006.

Sure enough, it is the afflicted A3 silicon. That explains it. I can fix it
in hardware... Don't really want to wait on a new chip.