16F88 Analog In

[Mugelpower]

Hi Gurus of Picland!

yeeees I know thats quite simple thing for you all and I could find it in the data sheet.....but thats my first time on 16F88 . LCD works of course, its just this ansel adcon thingy....
and i searched in the forum but everyone uses RA inputs for analog. They are used for the lcd so I like to use RB7 which hasnt anything else to do.

I would appreciate Your help.

code:
'************************************************* ***************
'* Name : Ananlog1.BAS *
'* Author : [select VIEW...EDITOR OPTIONS] *
'* Notice : Copyright (c) 2008 [select VIEW...EDITOR OPTIONS] *
'* : All Rights Reserved *
'* Date : 23.03.2008 *
'* Version : 1.0 *
'* Notes : 16F88 LCD 2x8 connected as ususal *
'* : Portb.7 analog IN 0-2V *
'************************************************* ***************


Include "modedefs.bas"



CMCON = 7 ' PortA = digital I/O
ANSEL = %00000110 ' Will set RB7 as analog I hope
ADCON0 = %11100001
ADCON1 = %10000010
adval var word 'Create adval to store result




Define ADC_BITS 8 'Set number of bits in result
Define ADC_CLOCK 3 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uSbut show on LCD Value:3
Define osc 4

loop: ADCIN 7, adval ' Read channel 0 to adval

Lcdout $fe, 1 ' Clear LCD
Lcdout "Value: ", DEC adval ' Display the decimal value

Pause 100 ' Wait .1 second

Goto loop ' Do it forever
End

[mister_e]

Your ANSEL setting is wrong... RB7 is AN6 and must be set to 1 in ANSEL bit 6.

Seems you revert bit order or something like that.

ANSEL=%76543210

[Mugelpower]

Mister_E,
thaks for your suggestion.

I tried several ansel settings

from
ANSEL=%01000000
to
ANSEL=%10000000
to
ANSEL=%01000110
and a dozen similar versions.

when I switch on the LCD shows for half a second "Value:03" and then
"Value:00"
Yes..its because of internal bit during startup.
Switched an Lcdout $FE,1,"Hello"
Pause 500
into just to show the PIC works and goes through the loop.

I could switch input to any RB exept RB03 which is used for the LCD.

Input voltage is now 0-2,5V .just for checking purposes.

Do I need a reference voltage?

[Acetronics2]

Hi Mügel

the obvious thing here ...

- is you select Channel 7 ( ADCIN 7 ),
- Choose channel 1 and 2 for the ADC ,
- choose channel 4 as default Analog channel,
- right justify the result ( Ok, here , why not ? ) ,
- use a 16 bits variable for the result,
- and , at last use an 8 bits conversion ...

Might I add your comment tells "read channel 0" for an " ADCIN 7 " ...


is that clear enough for you ???

Alain

[Mugelpower]

Hello Ace,

I changed (tried to) the channel but not the comment .

Puzzling together the analog thing is difficult for me as its the first time.
Did that with a 12F675 worked great.
You were second in the following "code saving contest": http://www.picbasic.co.uk/forum/show...ghlight=12F675

Now I try to save one simple 12F675 and I´m in trouble again.

No, What you told below isn´t clear enough for me although it shows the typical "Newbie defines rubbish"
in this thread:http://www.picbasic.co.uk/forum/show...ht=16f88+adcon
Melanie tells us that the adcon thingy affects only Porta.
But the data sheet page 114 tells us (you, not me) how to set the adcon0 register bit to select channel 6 = RB7.

So, thats REALLY irritating to me.

so I hope thats clear enough for you.

I know I´m juggling bits like shooting in the dark but its always the same:
search a code that works for me and then modifiing.
All codes used RA ports as analog input. Can´t use that.

[Acetronics2]

Hello Ace,

But the data sheet page 114 tells us (you, not me) how to set the adcon0 register bit to select channel 6 = RB7.

So, thats REALLY irritating to me.

so I hope thats clear enough for you.

.

Mhhhh,

I do not understand you : you ask for code ready to paste !!!

No, no, no ...



Forget the ' 675


Just take your '88 datasheet ADC section ...
READ it carefully,

beginning by the ANSEL config

WHAT do you have to write to select Channel 6 ( RB 7 ) ???

Now ADCON 0 Config

WHAT do you have to write to select RC clock ?, Channel 6 ?, AD OFF ( ADCIN will turn it ON in time )

Now, ADCON 1 Config

WHAT do you have to write to select Right justif. ?, Voltage refs ???

THAT's all you have to do ... but that must suit your harware config !!!


You don't see here ANY ref to other existing devices ... so, forget that " cut ( ? ) and paste" horrible habit.

Alain