"JDM" pic programmer 2
Is anybody using the JDM serial pic programmer?
I built the Pic-Programmer 2 version and I'm debugging it before pluging in a live pic. (www.jdm.homepage.dk/newpics.htm) It seems that the VPP (MCLR) pin goes from -.6v to +12.87 volts. I'm worried that the negative voltage (when it should be zero) might damage the device being programmed. I tried adding a 1n4148 clamp diode from MCLR to VSS (Anode to VSS) and that brings the 'zero' voltage down to -.37v or so. VDD runs +5.11v (exactly what the Zener diode is rated at). The +12.87v for vpp is about what it should be given the 8.2v and 5.1v zeners plus the drop through Q1 (and that 8.2v zener might be the low side, I didn't measure the drop across it). If the slightly negative voltage on MCLR isn't fatal, I guess the programmer is good to go. Any ideas? |
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