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[SOLVED]PIC18F4550 + HC-05 module receiving wrong characters
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pizdec

Joined: 21 Sep 2018
Posts: 6

Posted: Tue Oct 02, 2018 4:12 am

Ttelmah wrote:

As a further comment, the HC05, should not work with the 16F877A either,
unless you are either using the LF version of the PIC and running it at 3.3v,
or are using software RS232, rather than the hardware port (the software
serial has TTL input thresholds, rather than Schmitt thresholds).

The HC05, is based on the BlueCore4 chipset, and this does not produce
enough output voltage to drive the PIC hardware UART input pins on a 5v
PIC.

Have you got any test instruments at all?.
If you have a scope, you need to be looking at the waveforms. Does the
serial input to the PIC go up to at least 4v. It isn't going to work unless it
does.

Thank you. You were right, CPUDIV1 solved half of the issue, the other part was that I was receiving the '\r' char after every char, so I added a filter to avoid to take that char now it works fine.

It worked for the PIC18F4550 and working for the PIC16F877A.

A curious thing, I have 2 PIC16F877A, both are a bit different, one is '1441BE' and it always worked without this. But the other one is '12913B0', and it had the same issue as the PIC18F4550. Luckly I solved it for both of them by the same way. Smile

Ttelmah

Joined: 11 Mar 2010
Posts: 19215


Posted: Tue Oct 02, 2018 4:49 am

Normally PIC ID numbers are YYWWNNN. Your numbers don't look 'right' for this. Year of manufacture. Week. Alphanumeric manufacture location. Suggests one is perhaps an older batch, possibly with a lower input threshold, so it worked!... Ah. I realise you are giving the ID read from the programmer. The B0 one is a very old chip. Interesting that the newer one works better.

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