flashforth-devel

[Flashforth-devel] PIC18F UART problem

[Pablo M. <ea...@ho...>]

Hello,


I have recently compiled FF for a 18F26K20, using the last source code (ff-pic18.asm - 07.10.2017).


After power-up, the PIC sends the correct message ("FlashForth 5 PIC18F26K20 07.10.2017"). But when sending caracters from the terminal to the PIC there is no echo and no response to commands.


After some investigation, I have found that the problem is caused by these instructions inside WARM:


        clrf    TRISC, A
        clrf    LATC, A

Writing 0 to TRISC makes the pin RXD an output, so the UART can't receive. >From the datasheet:

For all modes of EUSART operation, the TRIS control
bits corresponding to the RX/DT and TX/CK pins should
be set to ‘1’. The EUSART control will automatically
reconfigure the pin from input to output, as needed.

I have commented the instructions and now everything works as expected.I suspect that this problem also affects other members of the family.

Previous versions of ff-pic18.asm didn't have these two lines of code (at least they were not included in version 19.01.2015). I would like to know what is its purpose.



Regards,


   73, Pablo - EA4FUK

Re: [Flashforth-devel] PIC18F UART problem

[Mikael N. <mik...@fl...>]

Hi.
Those were left there by mistake. The PORTC was used for debug leds.
The chips I use (18F2550 and 18F14K50) did not have your problem, so I 
did not notice it.

I will fix this in the next update.

BR M.

On 2017-12-18 11:44, Pablo Munoz wrote:
> After some investigation, I have found that the problem is caused by
> these instructions inside WARM:
> 
>         clrf    TRISC, A
>         clrf    LATC, A

Re: [Flashforth-devel] PIC18F UART problem

[Mikael N. <mik...@fl...>]

Or then I just did not notice, since I was focused on debugging the new 
USB driver
and I did not use the UART.
Actually the data sheets of 18F2550 and 18F14K50 mentions
that the UART PINS TRIS bits should be set to 1.

M.

On 2017-12-18 13:17, Mikael Nordman wrote:
> Hi.
> Those were left there by mistake. The PORTC was used for debug leds.
> The chips I use (18F2550 and 18F14K50) did not have your problem, so I
> did not notice it.
> 
> I will fix this in the next update.
> 
> BR M.
> 
> On 2017-12-18 11:44, Pablo Munoz wrote:
>> After some investigation, I have found that the problem is caused by
>> these instructions inside WARM:
>> 
>>         clrf    TRISC, A
>>         clrf    LATC, A

-- 
--
Mikael

Re: [Flashforth-devel] PIC18F UART problem

[Mikael N. <mik...@fl...>]

This issue has been fixed and pushed to git and to the downloadable zip 
file.
M.

>> On 2017-12-18 11:44, Pablo Munoz wrote:
>>> After some investigation, I have found that the problem is caused by
>>> these instructions inside WARM:
>>> 
>>>         clrf    TRISC, A
>>>         clrf    LATC, A