I have been messing with picstart again. I use it mainly for isp programming often it fails. so I got fed up with this and started to wonder why. I have always used a 10k pull up on mclr and a diode.
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on pins 1/ 4/ 14/ 32/ 40
from there I got a schematic and noticed that mclr is pulled low with a 5.1k so I my pull-up is now 33k because I think the 10k was not being pulled low enough and not allowing pic to reset.
What value resistor do you use as a pull up on mclr ?
After reprogramming my devices need to be resetted, so I don't have any timing difference or lock-ups when one of the devices is resetted.
I have several devices on the same MCLR which is pulled high by a MRS of
1k5. by selecting which program lines to be used (analog switches) I can decide which device to be programmed. But only the PGC and PGD are switched this way. Also al other chips (except the chips needed for programming) are disabled when MCLR goes low or above VPP(min).
When the chips go "online" again the mcu start finding each other and other chips for a full system check, only if passed they will go in normal usage mode.
When I checked the design I also used an MRS of 1k5 on a bread board simply because it was in front of me.
So don't bother to much about this pull-up but simply try some, if it goes wrong with programming check TFM (the @#$% manual) of your programmer for details. The difference lies most of the time with the programmer and how much the can drive low or high.
Greetings and good luck
Alexander (which has the bad habit of doing some overkill)
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