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 Post subject: PIC12F1501 Pin Configuration
PostPosted: Wed May 11, 2016 10:56 pm 
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Joined: Wed May 11, 2016 9:53 pm
Posts: 1
Hello everyone,

@Christian: First of all, many thanks for your work on PICPgm und for making it available at no cost!

So, I am trying to build my own LV-programmer with the help of my Raspberry PI respectively its GPIO Pins.
Anyway, my problem is that I can't really figure out which pins to use on my PIC. According to the schematic scetch on http://picpgm.picprojects.net/install_raspberry_pi.html, there are four pins (aside from voltage source and ground) that need to be connected to the programmer.
I already managed to identify three of them, namely PGD, PGC and MCLR, as they are actually self-explanatory with a quick glance at the datasheet:
Image
Pins 6 and 7 should correspond to PGC and PGD, Pin 4 should correspond to MCLR, although the signal MLCR seemes to be low-active.
1.) Does this require taking additional steps in hardware, or can I adjust this via pgmifcfg.xml by entering a 1 at the matching "invert"-entry?
2.) As I understand it, the PGM-pin corresponds to the VPP-pin of the PIC. However, in my case, VPP and MCLR share the same pin. Facing this, how am I able to program my PIC, as both signals need to be independent from each other? Or am I just misinformed?

Help is much appreciated! Thanks in advance!

EDIT:
Okay, I carefully walked through the LVP-Section of the PIC12F1501 datasheet and found out that my PIC probably is one of those more "grown-up" devices that doesn't have a PGM-pin anymore. Thus, in order to enter programming mode using LVP, the programmer needs to provide a 32-bit key sequence on PGD. Laudably, this is already implemented within PICPgm as stated here http://www.picprojects.net/forum/viewtopic.php?f=6&t=11808&sid=5b8c800467bbf81e7bbf6a0713f926fb.
Again, many thanks to Christian!

I would very much appreciate any confirmation of my "findings", and ideally a circuit example for building up my own programmer using an RPI. I suppose that I can't do anything wrong by using the minimum PIC circuit provided here http://picpgm.picprojects.net/hardware.html, can I? Whithout the PGM-path, of course. By the way, is the external quartz really necessary? I assumed that the progamming clock is provided by PGC?


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