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Compiler bug with setup_adc_ports in v4.109

 
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EdWaugh



Joined: 07 Dec 2004
Posts: 127
Location: Southampton, UK

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Compiler bug with setup_adc_ports in v4.109
PostPosted: Tue Aug 03, 2010 8:52 am     Reply with quote
Hi all,

I just thought I would show you something that seems to be a bug. I suppose it doesn't strictly count as a compiler bug as it is with one of the supplied functions, setup_adc_ports();

The problem is that on an 18F87J11 (80 pins and includes port H) I want to use H7 as an input but it was always reading zero despite having turned off all the additional pin functions. I was using:

setup_adc_ports(NO_ANALOGS);

Expecting this to set all ANx pins to be digital IO but it misses H7. Here is the listing of what it does including my interpretation:

Code:


Work = 0xff

....................    setup_adc_ports(NO_ANALOGS);                             
1945A:  BSF    FC0.4    - Set the ADSHR bit to 1 accessing ANCONX not ADCONX
1945C:  MOVWF  FC1   - Move 0xFF to ANCON0 setting all pins to digital IO
1945E:  BCF    FC0.4   - Clear the ADSHR bit to 0 accessing ADCONX not ANCONX
19460:  BCF    FC2.6   - Set -Vref = AVss
19462:  BCF    FC2.7   - Set +Vref = AVdd
19464:  BSF    FC0.4   - Set the ADSHR bit to 1 accessing ANCONX not ADCONX
19466:  MOVF   FC2,W    - Move the ANCON1 register to work (ANCON1 = 0x00 on POR)
19468:  ANDLW  80       - Work AND 0x80 (0x00)
1946A:  IORLW  7F   - Work OR 0x7f (0x7F)
1946C:  MOVWF  FC2   - Put the work register back into the ANCON1 register (Sets ANCON1 0x7F from POR leaving AN15 as analogue)
1946E:  BCF    FC0.4   - Clear the ADSHR bit to 0 accessing ADCONX not ANCONX


So ANCON1 gets set to 0x7f from the power up value of 0x00 which leaves pin H7 (AN15) as an analogue input (bit 7 is set to 0) rather than digital IO (bit 7 set to 1).

Please let me know if you think I have got this right. I have not looked into it any closer, I just wrote my own setup_a2d_ports function.

Cheers

Ed
mkuang



Joined: 14 Dec 2007
Posts: 257

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PostPosted: Tue Aug 03, 2010 9:59 am     Reply with quote
Looks like you are right.
EdWaugh



Joined: 07 Dec 2004
Posts: 127
Location: Southampton, UK

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PostPosted: Tue Aug 03, 2010 10:04 am     Reply with quote
Thanks!

I guess I should submit it as a proper bug report.
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