• AVR Freaks

Hot!PIC12F1572 using DAC output

Author
Ambient Power
New Member
  • Total Posts : 6
  • Reward points : 0
  • Joined: 2015/10/01 08:58:19
  • Location: 0
  • Status: offline
2019/07/16 03:56:54 (permalink)
0

PIC12F1572 using DAC output

So, I've tried on both the Curiosity LPC board and my own board, but all the time a programmer is connected, I get a poor output from the DAC (on RA0). It seems that the programmer drags the output down. Is there any way to make the programmer go properly high impedance, or do I need to add a manual switch to connect and disconnect the RA0 connection to the programmer - i.e. connect during programming, then disconnect afterwards? If I power up the board without the programmer connected, the output is fine, but it's inconvenient while developing, obviously.

Any ideas other than the switch?
#1

6 Replies Related Threads

    ric
    Super Member
    • Total Posts : 23859
    • Reward points : 0
    • Joined: 2003/11/07 12:41:26
    • Location: Australia, Melbourne
    • Status: online
    Re: PIC12F1572 using DAC output 2019/07/16 04:12:36 (permalink)
    0
    What programmer are you using?
    Most Microchip programmers have 10k pulldowns on PGC and PGD.
    I think the new PK4 may allow the pulldown to be disabled.
     

    I also post at: PicForum
    Links to useful PIC information: http://picforum.ric323.co...opic.php?f=59&t=15
    NEW USERS: Posting images, links and code - workaround for restrictions.
    To get a useful answer, always state which PIC you are using!
    #2
    Ambient Power
    New Member
    • Total Posts : 6
    • Reward points : 0
    • Joined: 2015/10/01 08:58:19
    • Location: 0
    • Status: offline
    Re: PIC12F1572 using DAC output 2019/07/16 05:12:48 (permalink)
    0
    I'm using an ICD3. I have loads of Pickit 3. I'll look into that, thanks.
    #3
    jack@kksound
    code tags!
    • Total Posts : 3209
    • Reward points : 0
    • Joined: 2014/05/14 10:03:19
    • Location: 0
    • Status: offline
    Re: PIC12F1572 using DAC output 2019/07/16 10:45:06 (permalink)
    0
    ric mentioned the pickit 4 NOT the pickit 3. Pickit 3 has 10k pull downs on the programming lines.
    #4
    Ambient Power
    New Member
    • Total Posts : 6
    • Reward points : 0
    • Joined: 2015/10/01 08:58:19
    • Location: 0
    • Status: offline
    Re: PIC12F1572 using DAC output 2019/07/16 14:27:47 (permalink)
    0
    Yes, I’m going to try a 4. Looked at the 3, might just take the 4K7s off. It’s the data line that’s interferes with as the DAC output has no drive capability.
    #5
    coffee critic
    Super Member
    • Total Posts : 377
    • Reward points : 0
    • Status: offline
    Re: PIC12F1572 using DAC output 2019/07/17 08:55:56 (permalink)
    0
    Per table 26-16 on page 281 the unit resistor value is 5k ohms.  ANY resistive load you put on the DACOUT pin will cause distortion from the expected output.  Your best solution is to remove the PICKit before testing the analog signal. 

    n_*$
    #6
    Ambient Power
    New Member
    • Total Posts : 6
    • Reward points : 0
    • Joined: 2015/10/01 08:58:19
    • Location: 0
    • Status: offline
    Re: PIC12F1572 using DAC output 2019/07/18 03:21:32 (permalink)
    0
    For now, I'm doing this. :)
     

    post edited by Ambient Power - 2019/07/18 03:22:56

    Attached Image(s)

    #7
    Jump to:
    © 2019 APG vNext Commercial Version 4.5