18F66J16 A/D operates only without ADIN

[Pictester]

Hello,

Here's a bit of feedback on my experience using the compiler to implement the analog to digital controller using the ADIN command with an 18F66J16.

The ADIN command worked fine with channel AD0 (pin 0 of port A) but for whatever reason it would not work on the pin 2 of Port A. Anyway, I used the assembler method given in the Microchip manuals and got it working. Maybe it's because the ANCON0 and ADCON0 registers, and the ANCON1 and ADCON1 registers share the same locations? This makes the sequence of things to do a bit different, vs. most other chips where there are ADCON0, ADCON1 and ADCON2 registers to cover all parameters without having to have two different registers occupy the same physical memory location. Note that I call each bit directly in these registers; calling the whole 8 bits at once still didn't work.

Anyway, here's the code that worked. And thanks to Mark Rodgers for helping me get the chip operating in the first place - your help is appreciated!

Any comments? Is this a problem with the chip or is there a way to get ADIN to work with the second channel AD2?

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-Tom
************************************************** **
Device = 18F66j16

CONFIG_START XT_OSC, WDT_OFF, PWRTE_ON, BODEN_ON, LVP_OFF, CP_OFF, CPD_OFF, DEBUG_OFF

CONFIG_END

OSCCON.6=1 'INTOSC is 8mhz
OSCCON.5=1
OSCCON.4=1
OSCTUNE.6=0 'switch off PLL for INT OSC
Declare XTAL 8
Symbol Get_Vbatt=PORTA.1 'get battery voltage signal
Symbol Debug_out=PORTB.5 'debug output line


Dim CR As Byte
CR = $0D
Declare ADIN_RES 10 ' 10-bit result required
Declare ADIN_TAD 32_FOSC ' RC OSC chosen
Declare ADIN_STIME 50 ' Allow 50us sample time
Dim VAR1 As Word
Dim X As Float
Dim Y As Float
Dim DEG As Float

TRISA = %00001101 ' Configure PORTA pins As inputs And outputs
WDTCON.4 = 1
ANCON0 = %11010010 ' Configure pins as digital or analog, AN0-AN7
WDTCON.4 = 0
ADCON0.7 = 0 'neg ref is AVss
ADCON0.6 = 0 'pos ref is AVdd
ADCON0.0 = 0 'A/D off
ADCON1.7 = 1 ' right justify
ADCON1.6 = 0 ' normal A/D operation
'******************************* Battery V*****************
WDTCON.4 = 0 ' choose ADCON location
ADCON0.2 = 0 ' pick channel 0 bit 1
ADCON0.3 = 0 ' pick channel 0 bit 2
ADCON0.4 = 0 ' pick channel 0 bit 3
ADCON0.5 = 0 ' pick channel 0 bit 4
ADCON0.0 = 1 ' turn on the A/D
DelayUS 100 ' Delay to allow A/D to stabilize
ADCON0.1 = 1 ' Start A/D - GO
DelayMS 1 ' Throw in amply delay to allow A/D to stabilize
VAR1 = (ADRESH << 8) + ADRESL 'put A/D variables into word
SerOut Debug_out, 84, ["Battery V level = ",HEX4 VAR1, CR]
Get_Vbatt = 0
'********************************************** Temperature
WDTCON.4 = 0
ADCON0.2 = 0 ' pick channel 2
ADCON0.3 = 1
ADCON0.4 = 0
ADCON0.5 = 0
ADCON0.0 = 1 ' turn on the A/D
DelayUS 500 ' Delay to allow A/D to stabilize
ADCON0.1 = 1 ' Start A/D - GO
DelayMS 1
VAR1 = (ADRESH << 8) + ADRESL 'put A/D variables into word - ADIN didn't work here
SerOut Debug_out, 84, ["Temp level = ",HEX4 VAR1, CR]

[Tim]

So to clarify what your saying, your having a problem with the ADin on a as yet unsupported device that you added the .lpb etc files for your self. The chip its self seems to be different in its configuration and will not even support the writing to a register in one go? (the way Proton would do it)

Now your wanting ADin to work on the higher channels despite you calming that you have it going already? Why?

BTW I see an issue with your code

VAR1 = (ADRESH << 8) + ADRESL 'put A/D variables into word

Its producing a lot of code for so little

All you need to do is

dim ADRESULT as ADRESL.word

VAR1 = ADRESULT

Thanks for point out a potential problem

BTW were is the ASM?

[Pictester]

Hi Tim,

Thank you for the reply. You are right, I'm not posting to ask for the solution to a problem and I'm not asking ADIN be implemented. I put in the submission to the group to provide the workaround I worked out for anyone else who will work with this chip in the future. I chose the "feedback" forum in case you are working on adding the 18F66J16 to the list of supported chips. If this is so, I would hope my message serves as a helpful observation. On another note, I've received so much help from this group that I feel I should contribute what I can when possible.

Of course, using ADIN is much simpler to use with fewer details to go wrong, so I prefer to use it over having a whack of register definitions to set up and change each time. So if ADIN is implemented for this chip, that would result in much fewer code lines (and the associated chance for error) for me and my people.

Regarding the assembler code - well, I described this as an "assembler" method but it isn't really the right term, I meant I was addressing each register bit individually rather than being able to use ADIN's much quicker functionality. The methods were derived by reading assembler examples from Microchip.

And thank you for the comment on the code.

-Tom