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SteveW
Joined: 27 Sep 2005
Posts: 25
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| PIC18F86K22 Port J [Solved] |
 Posted: Thu Sep 22, 2011 10:58 am |
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On a PIC18F86K22 I can't get get port J to function as digital I/O (all lines, specifically J2 and J3 appear to stuck as outputs). The seemingly relevant settings are:
| Code: |
#device adc=12
#device ICD=TRUE
#FUSES NOWDT
#FUSES ECM_IO //External clock, medium power
#FUSES PLLEN //4X HW PLL enabled
#FUSES NOPUT //No Power Up Timer
#FUSES MCLR //Master Clear pin enabled
#FUSES STVREN //Stack full/underflow will cause reset
#FUSES BBSIZ2K //2K words Boot Block size
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOPROTECT //Code not protected from reading
#FUSES NOCPB //No Boot Block code protection
#FUSES NOCPD //No EE protection
#FUSES NOWRT //Program memory not write protected
#fuses SOSC_DIG // Digital mode, I/O port functionality of RC0 and RC1
#fuses ABW8 // 8-bit bus (Micocontroller mode).
#use delay(clock=48000000)
setup_external_memory(EXTMEM_DISABLE);
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From the symptoms and the data sheet, it appears that the external memory interface is enabled. A curious observation is that when I delete the line immediately above that disables external memory, port E stops working as digital I/O (as expected), but port J starts acting as digital I/O, which is the opposite of what I expected.
Another curious observation is that the IDE shows that the ABW is set for a 20-bit bus, even though the ABW8 fuse should set it to an 8-bit bus (i.e., micro-controller mode). If I try to set the configuration bits for an 8-bit bus via the IDE (by un-checking the "Configuration bits set in code" box), after compiling, the bits go back to 20-bit mode. The LST file shows the ABW8 fuse as being set:
| Code: |
Configuration Fuses:
Word 1: DB15 VREGSLEEP INTRC_HP SOSC_DIG NOXINST ECM_IO PLLEN FCMEN IESO
Word 2: 7C79 NOPUT NOBROWNOUT BORV18 ZPBORM NOWDT WDT1048576
Word 3: 8BC9 RTCOSC_T1 EXTADDRSFT ABW8 BW16 NOWAIT CCP2C1 ECCPE MSSPMSK7 MCLR
Word 4: 0011 STVREN BBSIZ2K DEBUG
Word 5: C00F NOPROTECT NOCPB NOCPD
Word 6: E00F NOWRT NOWRTC NOWRTB NOWRTD
Word 7: 400F NOEBTR NOEBTRB
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Some fuses have been forced to be compatible with the ICD debugger.
The line immediately above is disconcerting.
Software versions:
MPLAB v8.76 with an IDC3
CCS v4.124
Any ideas? I am stuck.
Regards,
Steve
Last edited by SteveW on Sun Sep 25, 2011 6:05 pm; edited 1 time in total |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 22, 2011 1:27 pm |
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| Quote: |
I can't get get port J to function as digital I/O (all lines, specifically J2 and
J3 appear to stuck as outputs).
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Post a short, compilable test program where you show the problem.
Show the code where you attempt to read pins J2 and J3. Show or tell
how you know that it's not working. Are you using a Watch window in
a debugger ? Probably. If so, try using printf to display the results of
the read operation. In other words, let's remove the possibility of a
problem in the debugger/IDE. Compile and run it in release mode. |
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SteveW
Joined: 27 Sep 2005
Posts: 25
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| Posted: Thu Sep 22, 2011 3:53 pm |
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PCM Programmer,
Thank you for the reply. After more investigation, the port J pins are indeed set as inputs, but the internal pullups are not functioning. If I use an external pullup, operation is as expected. To enable pullups I use the command
port_j_pullups(TRUE);
Just in case this was implemented expecting individual pin selection, I tried
port_j_pullups(0xFF);
This doesn't work either.
There is nothing loading any of the pins I tried (J1-3).
The internal pullups are working fine on other ports.
I am not completely sure what you mean by "release mode". I have the ICD3 set as a programmer, not as a debugger. Is that what you mean?
Regards,
Steve |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 22, 2011 7:30 pm |
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The built-in function for port_j_pullups() is writing to PortG, which is
incorrect. This is with vs. 4.124. I made a bit definition and a macro to
replace the built-in function. Try the code shown below. See if it fixes
the problem.
| Code: |
#include <18F86K22.h>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT
#use delay(clock=4000000)
#bit RJPU = getenv("SFR:PADCFG1").5
#define port_j_pullups(x) x ? (RJPU = 1) : (RJPU = 0)
//==========================================
void main()
{
setup_external_memory(EXTMEM_DISABLE);
port_j_pullups(TRUE);
while(1);
}
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And yes, by "Release Mode", I do mean using the ICD as a programmer,
and not as a debugger. MPLAB has a drop-down box to select either of
those two modes. |
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SteveW
Joined: 27 Sep 2005
Posts: 25
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| Posted: Thu Sep 22, 2011 9:21 pm |
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Perfect! Thanks.
Where did you find the information that you used to determine that the PortJ function writes to PortG? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 22, 2011 10:07 pm |
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I compiled the test program that I posted (but without the 2-lines above
main). Then I looked at the .LST file in both Symbolic and normal CCS
modes. It showed that the PortG was being accessed. That didn't seem
right, so I checked the PIC data sheet and confirmed it. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Sep 25, 2011 2:51 pm |
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I emailed CCS support about this just now. I also found that it affects
the enable pullups functions for PortD and PortE in addition to PortJ.
I told them about that too. |
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SteveW
Joined: 27 Sep 2005
Posts: 25
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| Posted: Sun Sep 25, 2011 6:03 pm |
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| Thank you for the explanation. Your approach will likely come in handy. |
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