Problem with programming dspic30f as reset circuit is blocking MCLR

[hansika]

hi all,
i am dumping hex file in dspic30f6014A using parallel port(TAIT ckt) and the software i am using is winpic 800(propic2) i am able to dump the code successfully but here the problem is i need to remove the reset circuit every time to dump the code i.e when i am connecting the controller and programmer with reset(RC circuit) circuit present controller is not identifying however if i remove the reset circuit the programmer is working fine . why this is happening can't we program a controller in presence of Reset circuit.

 

[keith1200rs]

Re: programming dspic30f

[reply deleted - complete rubbish! Message to self - "read questions properly"]

Keith.

 

[FvM]

Re: programming dspic30f

Apparently the reset circuit is blocking the MCLR line, that is needed by the ICSP protocol. A 10k series resistor between reset circuit and MCLR pin usually helps, otherwise I would doubt the programmer to be badly designed. Microchip programming adapter (ICD etc.) user manuals have clear reuirements for the circuitry allowed at each ICSP pin.

 

[hansika]

Re: programming dspic30f

here i am giving my connection diagram. in presence of rc circuit controller is not identifying and if we remove the RC circuit then it is working fine can you please tell me where the modification is needed. in presence of RC ckt program in the controller is running.

 

[keith1200rs]

Re: programming dspic30f

You need a jumper to be able to remove the capacitor. If you look at the Microchip development boards they usually have a jumper. Do you actually need the capacitor?

Keith.

 

[hansika]

Re: programming dspic30f

Here mclr is active low pin and RC circuit decides the time constant for reset. i think if we directly give the supply also no problem program will start. actually my PCB is already designed otherwise i will place jumpers as you suggested. here my problem is everything is finalized(PCB) but if i want to dump another program i need to remove and put the RC components again every time, i am searching is there any solution for this or not.

 

[keith1200rs]

Re: programming dspic30f

But do you need the capacitor? I haven't used the dsPIC, but with the PIC24HJ I haven't needed it. The chip doesn't run until after the brownout reset voltage has been achieved and you can add a brownout delay as well; and there is also an additional power up delay that can be added after that (up to 128ms on the PIC24HJ). I would have thought the external capacitor would be superfluous.

Keith.

 

[FvM]

Re: programming dspic30f

Apparently, Microchip has already experienced designers not reading the clear suggestions for programmer circuit in the datasheet. I also thought (apparently in vain) that my previous post had been clear so far. :sad:
They published a simple, understandable graphic for this reason



As said, a 10k resistor between the reset circuit and the MCLR pin did work with any PIC type I used up to now.

 

[hansika]

Re: programming dspic30f

hi, here i have made some observations i have made in my circuit, when i am connecting the the programmer(TAIT classic) to the controller and when i am pressing the detect PIC type button in winpic800 (software i have used this) i measure the voltages at the mclr pin
when RC circuit not present voltage is 0.6V at mclr pin and controller type is identifying
when RC circuit present voltage at mclr pin 2.6V and program in controller is running and controller type is not identifying.
below is the circuit of my programmer here i have not used the diode at mclr pin

 

[keith1200rs]

It is a good job you don't use the diode - it is the wrong way round.

I think you should try the suggestion made earlier and remove the capacitor on your MCLR pin.

Keith.

 

[FvM]

I think you should try the suggestion made earlier and remove the capacitor on your MCLR pin.

Yes. The Microchip recommendations should make your circuit work with any standard ICSP programmer. You can of course try to modify the programmer to work with a non-standard MCLR circuit. But there are some limitations: If you have e.g. the output of a reset generator connected to MCLR without a series resistor, you'll either burn the programmer or the reset circuit.