On 21/11/2010 01:23, Jan-Erik Soderholm wrote:
> I think like this...
>
> Right, you can setup the pot to give 2.5V at the input
> using a voltmeter. But then what ? Will you always
> use a voltmeter when setting the pot ?
>
> What does it matter if the motor stands still with 2.4V
> or 2.6V at the ADC input ? The visual difference in the
> setting of the pot would probably be very small. What kind
> of pot is it ? A regular 1-turn or some 10-turn pot ?
>
> I'd also guess that the differense between the ADC value
> with Vpp/2 (5V/2, right?) will be quite small compared with
> the theoretical half-range value (according to the datasheet).
> Probably just +/- a few bits, after all, that is what the
> datasheet specifies. And probably smaller then any visable
> difference from the mid-position setting of the pot.
>
> *Or* I must seriously be missing something here. :-)
>
> Jan-Erik.
>
>
>

Yes, I see it similarly - a bit of adjusting and gathering empirical=20
data will often suffice for this kind of thing, where the tolerances are=20
reasonable.
However, I can understand the desire to get the hardware debug working=20
as it is undoubtedly a useful tool to have available in general.
For instance, I used to get along without my ICD3 just fine, using=20
things like LEDs or bit banged UART for debugging, but it's certainly=20
more convenient (IMHO) to use the ICD3 and have it all contained within=20
MPLAB.
If I understand where James is coming from, it's not so much the fact=20
that he needs it to make things "possible", just maybe a bit easier.
Plus, there's the frustration when something is meant to work but=20
doesn't, most engineers (me included) find it hard to leave a problem=20
"unsolved", even if it doesn't actually matter much to the whole=20
project...  :-)



>
>
>
> On 2010-11-21 01:38, James Newton wrote:
>> Think about that for just a second?
>>
>> If I /knew/ the value of ADRES to inject, why would I be trying to find =
it?
>>
>> --
>> James Newton
>> 1-970-462-7764
>>
>> -----Original Message-----
>> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf=
 Of
>> John Temples
>> Sent: Saturday, November 20, 2010 16:24
>> To: Microcontroller discussion list - Public.
>> Subject: RE: [PIC] pickit2 unreliable debug 12F675
>>
>> On Sat, 20 Nov 2010, James Newton wrote:
>>
>>> In this specific case: I have a pot connected to AN0 and set so that 2.=
5v
>> is
>>> on the pin. Now I want to know exactly what ADC count the chip is readi=
ng
>> so
>>> I can set that as the midpoint in my code and turn the motors one
>> direction
>>> when the voltage is lower and the other when it is higher.
>>>
>>> With a debugger, I simply read the ADC output register and I'm done.
>>>
>>> How would you get that value without the debugger?
>> The simulator has a register injection feature that reads hex values
>> from a file that are injected into ADRES over time.
>>
>> --
>> John W. Temples, III


--=20
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