12f675 and midi!

[Alaskanphoenix]

I want to use gp0 and gp1 as analog inputs and gp3 as digital out to send midi messages:

DEFINE OSC 20
DEFINE DEBUG_BAUD 31250 ' midi baud rate
DEFINE DEBUG_REG gpio ' Set Debug pin port
DEFINE DEBUG_BIT 2 ' Set Debug pin bit
DEFINE DEBUG_MODE 0

adval var byte ' Create adval to store result
ANSEL = %00000011 ' ----DDAA
CMCON = 7 ' Analog comparators off

loop: ADCIN 0, adval ' Read channel 0 to adval
debug $b0,$00,adval
Pause 250 ' Do it all about 10 times a second
Goto loop ' Do it forever

End

how can i limit the results of analog inputs between 0-127?

Thanks a lot

[mischl]

divide adval by 2

adval = adval / 2
adval = adval >> 2

[Alaskanphoenix]

Thank you all very much!
It finally works!

I use the Hs oscillator and it works ok!

One last question, why if i connect a pot in gpio.0 and rotate it the numbers don't start from 0 but from $7f, go to 0 and arrive to $7f?

i use adval >> 2 to limit till $7F

Thanks

[mischl]

the pot values goes from 127 to 0 instead 0 to 127?

then change the plus and minus on your pot, that changes the direction

[Alaskanphoenix]

The pot starts from $7f, decreases till 0 and goes to $7f in the same direction!
But i used advar = advar >> 1 instead of >> 2, because the second starts from $3f to 0 to $3F!

Why?

[TonyA]

I'm also into MIDI. I've made a midi sender with the 18F452 and was wondering about the 12F683. But since it didn't have HSEROUT I wasn't sure if it would work. So it seems it can work with serout using a 20 Mhtz xtal?

Something I'm confused about however is the setting up of the ANSEL.
I see that in the example above by Ingvar there are 2 bits that are set high along with the appropriate pins: like this ANSEL %00110011, but in Allaskan's example he just does this: ANSEL %00000011

So GPIO.0 and GPIO.1 are analog inputs, but what do the 1's in position 4 and 5 represent?
What is the ADCON0 doing?

Also, why do you have to disable the analog comparators?

Thank,
Tony

[Alaskanphoenix]

HI Tony,
i used to send midi messages with the serout2 command at 31250 only with 16 and 20 mhz xtals and it works!

If you look at the datasheet of the 16f675 everything is revealed to you!

I think that ANSEL %00110011 sets the ad conversion clock to FRC and gp0 gp1 to ad inputs.

ADCON0 is the A/D CONTROL REGISTER, you use it if you want to set the conversion less automated.

I disable the comparators only for precaution!

bye