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picj1984
Joined: 01 Mar 2010
Posts: 73
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| reassign Tx on #use rs232 as general purpose IO? [SOLVED] |
 Posted: Tue Apr 17, 2018 1:22 pm |
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Hello,
I'm not using the TX pin on my UART module. Can I reassign that for general IO usage? Right now I'm just trying to do the output_low() function but it's just always staying high.
Joel
Last edited by picj1984 on Fri May 04, 2018 3:40 pm; edited 1 time in total |
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temtronic
Joined: 01 Jul 2010
Posts: 9244
Location: Greensville,Ontario
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| Posted: Tue Apr 17, 2018 1:47 pm |
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yes, you should be able to, but you need to post which PIC and compiler version , so that others can test to confirm .
It could be a simple premade function or you may have to code yourself, that's why compiler version is nice to know. |
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picj1984
Joined: 01 Mar 2010
Posts: 73
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| Posted: Tue Apr 17, 2018 2:28 pm |
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| temtronic wrote: | yes, you should be able to, but you need to post which PIC and compiler version , so that others can test to confirm .
It could be a simple premade function or you may have to code yourself, that's why compiler version is nice to know. |
oops sorry about that. It's a PIC16F1825 and I'm using PCM Compiler V4.140. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19543
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| Posted: Wed Apr 18, 2018 12:41 am |
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You have to do a little bit more fiddling. Thing is that for the code to use the hardware UART it has to be told to use _both_ pins. This then leaves the TX pni being driven by the UART. So the key is to turn this off:
| Code: |
//Processor include
//fuses
//clock declaration
#use RS232(UART1, BAUD=9600, ERRORS)
//Standard UART enable on the default hardware pins
//Then
#BIT TXEN=getenv("BIT:TXEN")
//This now gives us access to the UART TXEN bit
void main(void)
{
TXEN=FALSE; //Turn off the UART transmit
//You can now read and write the TX pin normally
while(TRUE)
;
}
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As you can see it is very easy. All you do is enable the UART normally, and then turn off the transmit 'side' of the hardware. |
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picj1984
Joined: 01 Mar 2010
Posts: 73
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| Posted: Fri May 04, 2018 3:41 pm |
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| Ttelmah wrote: | You have to do a little bit more fiddling. Thing is that for the code to use the hardware UART it has to be told to use _both_ pins. This then leaves the TX pni being driven by the UART. So the key is to turn this off:
| Code: |
//Processor include
//fuses
//clock declaration
#use RS232(UART1, BAUD=9600, ERRORS)
//Standard UART enable on the default hardware pins
//Then
#BIT TXEN=getenv("BIT:TXEN")
//This now gives us access to the UART TXEN bit
void main(void)
{
TXEN=FALSE; //Turn off the UART transmit
//You can now read and write the TX pin normally
while(TRUE)
;
}
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As you can see it is very easy. All you do is enable the UART normally, and then turn off the transmit 'side' of the hardware. |
Just realized I never came back to say "thanks!" this is working for me now  |
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gjs_rsdi
Joined: 06 Feb 2006
Posts: 468
Location: Bali
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| rs232 on/off |
| Posted: Mon Nov 28, 2022 5:09 am |
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I know this topic is very old but I want to thank you Ttelmah for explaining how to enable/disable the TX pin
Best wishes
Joe |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19543
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| Posted: Mon Nov 28, 2022 8:04 am |
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Well done that you found this. 
99% of things like this have been answered here, which is why using the
search is such a powerful tool.
For some answers things have later 'evolved'. So (for example) there are
threads a few years ago on how to manually set ANSEL, which have now
been made redundant with CCS adding this to set_adc_ports). However
most of the answers still apply as they did when originally made.
Glad you have it doing what you want. |
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gjs_rsdi
Joined: 06 Feb 2006
Posts: 468
Location: Bali
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| Posted: Mon Nov 28, 2022 9:21 am |
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Definitely the forum search is one of the best tools available.
You spend some time, but you save much much more
Best wishes
Joe |
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