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Hot!PIC18F24Q10 output voltage

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The_Hyren
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2019/11/11 13:56:37 (permalink)
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PIC18F24Q10 output voltage

I recently picked up a PIC18F24Q10 to act as a controller for an I2C networked power supply I'm designing. Despite the device being listed as an F and not LF and it being able to run using 1.8 to 5.5V for VDD it will only output up to 3.3V. Is it a 3.3 logic chip or is there a trick to get VDD? I need 5V to run a power NMOS and would prefer to not have to add other components.
 
Also I am having issues with the WPU on RB1 not working but the spec sheet doesn't mention that it doesn't exist.
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    ric
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    Re: PIC18F24Q10 output voltage 2019/11/11 14:37:07 (permalink)
    +1 (1)
    The datasheet does state it can drive up to "Vdd - 0.7V" at 6 mA, so it should work. Are you sure Vdd is 5V ?
    What is the "power NMOS" ? Does it have any pulldown/pullup?
     

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    The_Hyren
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    Re: PIC18F24Q10 output voltage 2019/11/11 14:46:14 (permalink)
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    I read that as well but my DMM is saying VDD is 4.99V and RC0 is at 3.35V. All other B and C ports I've tested are also this way. All my As are ADC reads so I haven't tested them. TRISC are all 0 for output and LATC are all 1s as well. I have the RCxPPS all set to 0 so there should be no module interference either. Maybe these are more ESD sensitive then I'm used to and I zapped it? I have bought a few more to see if this device is just toasted.
    #3
    ric
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    Re: PIC18F24Q10 output voltage 2019/11/11 14:48:19 (permalink)
    +1 (1)
    Just a thought, are you sure your chip is running correctly, and not resetting over and over due to a misconfigured watchdog?
     

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    The_Hyren
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    Re: PIC18F24Q10 output voltage 2019/11/11 14:51:30 (permalink)
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    Quite sure as I have been following it in debug mode so I can check the values of the port registers. Very confused as to why it is not working. The insides all seem to run just fine.
    #5
    ric
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    Re: PIC18F24Q10 output voltage 2019/11/11 14:54:50 (permalink)
    +1 (1)
    ok. I just have that suspicion whenever anyone reports a low voltage from a DMM rather than a scope. Often they are really seeing an average voltage of a switching waveform.
    There's nothing in the errata for that device relevant to this. It might be time to open a support ticket at
    http://microchip.com/support
     
     
     

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    #6
    The_Hyren
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    Re: PIC18F24Q10 output voltage 2019/11/11 15:00:29 (permalink)
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    I did not think about it being a waveform but with the RCxPPS pin set to the LAT and at very low clock speed in debug I'm not sure how that could happen. I suppose I'll break out the scope
    #7
    mpgmike
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    Re: PIC18F24Q10 output voltage 2019/11/12 10:32:55 (permalink)
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    Just some random thoughts; look at your ODCONx and ANSELx values.  According to Electrical Specifications Table 38-4, D370, minimum output voltage = Vdd - 0.7 volts.  In your case, should be >4.3 volts.
     
    Can you isolate these pins (perhaps another PIC on a breadboard) and see what the output voltages are without being connected to the circuit?  That would at least determine if the Q10 is at fault (or even faulty) or if something external is affecting voltages.

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    #8
    Jerry Messina
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    Re: PIC18F24Q10 output voltage 2019/11/12 12:17:34 (permalink)
    +1 (1)
    I can attest to the fact that the output voltage on an unloaded 18FxxQ10 IO pin is basically VDD, so if you're seeing 3.3V there's something amiss somewhere.
     
    #9
    The_Hyren
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    Re: PIC18F24Q10 output voltage 2019/11/12 14:31:42 (permalink)
    +1 (1)
    ODCON, SLRCON, and ANSEL are all set to 0 except for a couple port A pins I am using with the ADC.
     
    This pic is on a breadboard and I have removed the components attached to them while using my DMM.
     
    I'm just assuming this pic has been esd damaged or something. I've acquired a few more.
    #10
    mpgmike
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    Re: PIC18F24Q10 output voltage 2019/11/12 16:17:32 (permalink)
    +1 (1)
    Excellent.  Try a different physical chip.  Sometimes they do get damaged.

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    The_Hyren
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    Re: PIC18F24Q10 output voltage 2019/11/12 17:45:17 (permalink)
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    Second chip is better but I am having some odd behavior with RC1 and RC0. They seem to be sitting at 3.3 and 2.6 volts and are sinking enough current to run to LEDS on that channel. I have RC1PPS and RC0PPS set to zero and the LAT set to 1 but they are still sinking current. ODCON and SLRCON and ANSEL all also set to zero for all of port C. Is there another peripheral I need to disable?
    #12
    ric
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    Re: PIC18F24Q10 output voltage 2019/11/12 17:47:27 (permalink)
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    A quick glance at the datasheet reveals that the secondary oscillator is on those pins.
     

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    #13
    The_Hyren
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    Re: PIC18F24Q10 output voltage 2019/11/12 17:49:53 (permalink)
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    Ok. that would explain things. How do I turn them into normal pins?
    #14
    ric
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    Re: PIC18F24Q10 output voltage 2019/11/12 18:00:25 (permalink)
    +1 (1)
    Make sure none of your CONFIG settings activate the SOSC.
    Also make sure the SOSCEN bit in OSCEN is not set.
    You will need to check through the datasheet to see what else might enable it.

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    #15
    The_Hyren
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    Re: PIC18F24Q10 output voltage 2019/11/12 18:10:13 (permalink)
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    I did have the OSCEN on so I fixed that. The configs don't mention it anywhere. It did reference T1/3/5GCON so I'll check those
    #16
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