PBP migration from 16F88 to 16F1827

[RussMartin]

Okay, I'm overlooking something. This program worked (albeit slowly) on a 16F88.

5 analog pins sample and (after manipulation) produce a high or low to a pin. Here's the correspondence:

AN0 to B5
AN1 to B4
AN2 to B3
AN3 to B2
AN4 to B1

AN5 and AN6 each have the wiper of a different pot on them.

Now, only AN4 to B1 works correctly. B5 is stuck high all the time (from power-up), even with no signal on AN0. The three in between are off if there is no signal but stick high as soon as a small signal is applied and remain that way until power-down.

The pot on AN5 has the correct effect on the one working channel but AN6 does not appear to be working.

Here's what I had in the (totally working) 16F88 version:

DEFINE OSC 8

ANSEL= %01111111
CMCON= %00000111
OSCCON= %01110000
TRISA= %01111111
TRISB= %11000001

ADCON1.7=1

DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 5
DEFINE ADC_SAMPLEUS 12

. . . and here's what I have for the 16F1827:

DEFINE OSC 32

ANSELA= %00011111
ANSELB= %11000000
OSCCON= %11110000
TRISA = %01111111
TRISB = %11000001

ADCON1.7 =1
CM1CON0.7=0
CM2CON0.7=0

DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 6
DEFINE ADC_SAMPLEUS 12

What thing(s) am I failing to do?

[RussMartin]

I discovered the capacitive sensing module and have added:

CPSCON0.7=0 to turn it off.

The effect was that the one working channel continues to work.

The pot on AN6 also now works.

But now all the other four channels lock high at power-up, even with no signal, and stay there.

I guess that's a tiny speck of progress.

[mackrackit]

I have had trouble in the past with the built in ADC commands.
You may want to try the method used here.
http://www.picbasic.co.uk/forum/show...2&postcount=16

[RussMartin]

I've also tried to make sure the CCP/ECCP modules were off by adding:

CCP1CON=%00000000
CCP2CON=%00000000
CCP3CON=%00000000
CCP4CON=%00000000

No change from previous result.

[Darrel Taylor]

What thing(s) am I failing to do?

Well, you failed to include the part that reads the A/D, "Manipulates" it, then outputs it to a pin.
<br>

[RussMartin]

I didn't include anything else because (a) everything ran fine on the '88 and (b) one of the five identically-processed channels is working just fine.

All five channels are handled like this (different VARs, of course) in a loop, with the interrupt enabled:

FOR SAMPLX=4 TO 1 STEP -1
ADCIN 2,INMD
IF INMD>TEMPMD THEN TEMPMD=INMD
NEXT SAMPLX
INMD=TEMPMD
IF MODE=1 THEN GOTO HOP3
IF INMD>341 THEN
INMD=(INMD-342)*3
ELSE
INMD=0
ENDIF
HOP3:
IF INMD<10 THEN COMP=0
IF INMD<THRES THEN INMD=THRES+INMD+COMP
INMD=INMD+COMP
IF INMD>1023 THEN INMD=1023
TEMPMD=0
XMD=INMD/2

The INT_INT handler looks like this:

STATE:
FOR INDEX=511 TO 1 STEP -1
IF INDEX=XLO THEN OLO=1
IF INDEX=XLM THEN OLM=1
IF INDEX=XMD THEN OMD=1
IF INDEX=XMH THEN OMH=1
IF INDEX=XHI THEN OHI=1
NEXT INDEX
OLO=0 : OLM=0 : OMD=0 : OMH=0 : OHI=0
@ INT_RETURN

[RussMartin]

Here it is:

@ __config _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _MCLRE_OFF & _BOREN_OFF & _FCMEN_OFF
@ __config _CONFIG2, _STVREN_OFF & _LVP_OFF

OLO VAR PORTB.5
OLM VAR PORTB.4
OMD VAR PORTB.3
OMH VAR PORTB.2
OHI VAR PORTB.1

DEFINE OSC 32

ANSELA= %00011111
ANSELB= %11000000
CCP1CON=%00000000
CCP2CON=%00000000
CCP3CON=%00000000
CCP4CON=%00000000
OSCCON= %11110000
TRISA = %01111111
TRISB = %11000001

MAIN:
OLO=1 : PAUSE 1000 : OLO=0
OLM=1 : PAUSE 1000 : OLM=0
OMD=1 : PAUSE 1000 : OMD=0
OMH=1 : PAUSE 1000 : OMH=0
OHI=1 : PAUSE 1000 : OHI=0
GOTO MAIN

END

No ADCs, no triac output, nothing but outputs low to high and back.

Results:

Each channel comes on in succession. The first four, however, than simply stay on. The fifth goes on and off exactly as you would expect.

I even tried this on a "fresh" '1827. No difference.

This is why I remain convinced that the problem hides in how I'm configuring something that affects B.2 through B.5 but permits B.1 to operate normally.

[Darrel Taylor]

Try this Russ,

OLO     VAR LATB.5
OLM     VAR LATB.4
OMD     VAR LATB.3
OMH     VAR LATB.2
OHI     VAR LATB.1

<br>

[RussMartin]

Sonofagun! It works. Thanks!

What did we just do?

And why was PORTB.1 working but not the others?

[Archangel]

Sonofagun! It works. Thanks!

What did we just do?

And why was PORTB.1 working but not the others?

. . . and what is the "real" difference between LATB & PortB ?
I am sensing a RMW issue . . . Thanks Darrel, in advance.

[Darrel Taylor]

It's the old R-M-W issue (Read-Modify-Write).

PIC's can't write to individual Pins in a PORT. It's not possible for the hardware to just set a pin high or low directly.
It has to Read the entire PORT, Modify the bit it wants to change, then Write the value back to the Entire PORT.
When it Reads the PORT, it actually reads the state of the Pins, not the state it was told to be in last.

In your code ...

MAIN:
    OLO=1 : PAUSE 1000 : OLO=0
    OLM=1 : PAUSE 1000 : OLM=0
    OMD=1 : PAUSE 1000 : OMD=0
    OMH=1 : PAUSE 1000 : OMH=0
    OHI=1 : PAUSE 1000 : OHI=0
GOTO MAIN

The OLM=1 statement is executed immediately(125nS) after the OLO=0 statement.
If the voltage on the OLO pin has not reached the level required to register a 0, then it reads OLO as 1 and writes that back to the PORT, ignoring that fact that you just told it to be 0.
Capacitance on the Pin will increase the amount of time it takes to reach the requested state.
Solderless breadboards can add quite a bit. LED's add some too.

Just like the 18F's, the 16F1's have LATx (DATA LATCH) registers.
If you use PORTB.0, it does the RMW on the PORT, then writes it to the LATB register which controls the pins state.

If you write directly to LATB.0, it doesn't read the port first.
It still does a read-modify-write, but what it reads is the LATB value (last requested state), not the state of the Pins.

DO NOT! use HIGH, LOW, TOGGLE, or any other PBP commands like SERIN/OUT, PULSIN/OUT etc. with LATx.x as a Pin.
It will cause big problems.

But writing to the LATx bits directly with a 1 or 0 can eliminate the dreaded R-M-W problem.

hth,