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Switching inLVL register in EUSART

 
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Bieli



Joined: 15 Sep 2003
Posts: 9

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Switching inLVL register in EUSART
PostPosted: Wed Mar 24, 2021 4:34 pm     Reply with quote
Hi,

PIC 16F18456
CCS 5.084

Standard problem 5V PIC and 3.3 UART device. Of course it won't work because PIC input High is >0.8Vdd.

Can I change INLVL register to work as TTL not ST? This would solve this problem (I think). Of course 3.3V device must tolerate 5V input.

I didn't find information how to change INLVL register in CCS. Any suggestion?

Regards
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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Re: Switching inLVL register in EUSART
PostPosted: Wed Mar 24, 2021 4:47 pm     Reply with quote
Bieli wrote:
I didn't find information how to change INLVL register in CCS. Any suggestion?


In the current version of the compiler, it has the set_input_level_x()
function, where 'x' is the port a, b, c, etc.

The CCS manual says:
Quote:

Function:
These functions allow the I/O port Input Level Control (INLVLx) registers
to be set. Each bit in the value represents one pin. A 1 sets the
corresponding pin's input level to Schmitt Trigger (ST) level, and a 0 sets
the corresponding pin's input level to TTL level.


If that's not supported in your version, then use this (for example):

Put this line above main():
Code:
#byte INLVLA = getenv("SFR:INLVLA")

Then in main(), do this:
Code:
INLVLA = 0x01;  // To set pin A0 to be a Schmitt Trigger input
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