alunaro
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Hello.
I'm trying to create an automatic switcher for the programming signals to isolate the ports when the ICD3 is programming and reverting to normal ports after.
The problem i have is when i try to interface the VPP line, because the target device is not recognized and many times the ICD3 becomes erratic and stop working propertly havin to disconnect it and reconnect again.
The idea is having something like:
It's just an idea, and doesn't work as shown. Said in other words i need to supply my own VPP instead the supplied by the ICD3 only if it's programming, so the circuit must detect this fact then switch to the other supply.
The problem as i said is it doesn't work so easily because the ICD3 usually lost the target, the communication or other weird things... It only happens with VPP because i could successfull interface the other lines.
I know VPP is quite sensitive to capacitance and impedance but the info supplied by Microchip doesn't look very clear for me.
If anyone could help or suggest some idea, welcome
I have to say i burned an ICD3 trying to interface it... a misterious thing really because the affected signals (PGD and PGC) were isolated by 2 protection circuits and there were no path between them and the voltage that -i suppose- burned them. Trust me when i say it was like a Poltergeist, i revied the circuit and it was impossible what happened but.. it did xDDD. So i'm quite cautious now with my new and last ICD3.
I'm trying to create an automatic switcher for the programming signals to isolate the ports when the ICD3 is programming and reverting to normal ports after.
The problem i have is when i try to interface the VPP line, because the target device is not recognized and many times the ICD3 becomes erratic and stop working propertly havin to disconnect it and reconnect again.
The idea is having something like:
It's just an idea, and doesn't work as shown. Said in other words i need to supply my own VPP instead the supplied by the ICD3 only if it's programming, so the circuit must detect this fact then switch to the other supply.
The problem as i said is it doesn't work so easily because the ICD3 usually lost the target, the communication or other weird things... It only happens with VPP because i could successfull interface the other lines.
I know VPP is quite sensitive to capacitance and impedance but the info supplied by Microchip doesn't look very clear for me.
If anyone could help or suggest some idea, welcome
I have to say i burned an ICD3 trying to interface it... a misterious thing really because the affected signals (PGD and PGC) were isolated by 2 protection circuits and there were no path between them and the voltage that -i suppose- burned them. Trust me when i say it was like a Poltergeist, i revied the circuit and it was impossible what happened but.. it did xDDD. So i'm quite cautious now with my new and last ICD3.
