That circuit is totally wrong and will give problems. the R& C on Vpp/MClr MUST be diode isolated. The programmer must not "see" a capacitor on VPP/MCLR. The R of the Reset RC can and is recommended to have a 2nd diode (1N4148 or 1N916 etc) to discharge C when there is a short power glitch. ICSP pin must connect direct to CPU MCLR pin
Isolate rest of circuit VDD/+5V from ICSP/CPU with a jumper or better a Schottky diode. A capacitor on power up reset is optional. Improves reset reliability, but only if the R feeding it has a reverse diode. The minimum MCLR/ Reset VDD/VPP is a single diode from +5V PSU to PIC and connect PIC MLCR and Programmer VPP direct. The best solution uses 3 diodes (cheap 1N4148 or 1N916 etc), 100nf capacitor and 10K to 47K resistor for MCLR pin on CPU and ICSP connector (the CPU MCLR and ICSP VPP/MCLR connect direct, no resistors or capacitors) Best solution on PSU / rest of circuit to CPU VDD pin and ICSP is connect the two direct and have a good Schottky diode or a jumper from the rest of target board to the cpu VDD pin(s). 100nF capacitor (no larger) on the VDD/VSS pins. Other PSU decoupling on the main board side of jumper/diode of +5V rail. I have to go out. I will upload the proper circuit later when I come back. (as per earlier Microchip doc and best engineering practice). On Mar 26, 4:45 am, mattschinkel <[email protected]> wrote: > You guys can check /trunk/doc/dita/tutorials/images/icsp_circuit.jpg > > But, I still think there should be a jumper in there at VDD. I am > using PIC KIT 2 (clone) programmer now. The microchip software has a > button to select weather to turn on 5v VDD. Other programmers do not > have this in software so maybe it should be in hardware. > > I also took a look at Jaluino schematic and I see no capacitor for > power-up reset, why is this? Is it not > needed?http://www.justanotherlanguage.org/sites/default/files/jaluino_medium... > > Thanks, > Matt. -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
