ISP

[Bill Meyer]

I planned on using ISP to flash my pic16f374, but seem to be missing something. The clock has to be running for ISP to work, and yet I cannot get my crystal to run until the proper config bit is set (default= RC). On the prototype I can put an RC in until the first flash is complete, but don't want to do that in production. Is this a catch-22, or am I missing something?

thanks.....
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This message was ported from CCS's old forum
Original Post ID: 8472

[J.Baxter]

:=I planned on using ISP to flash my pic16f374, but seem to be missing something. The clock has to be running for ISP to work, and yet I cannot get my crystal to run until the proper config bit is set (default= RC). On the prototype I can put an RC in until the first flash is complete, but don't want to do that in production. Is this a catch-22, or am I missing something?
:=
:=thanks.....

You shouldn't need the OSC clock running during ISP. Just make sure that you have connected all the ISP signals - 0V, +5V, MCLR, PGC(RB6), and PGD(RB7).

You will also need to isolate the rest of your pcb from the PIC signals used for programming. Otherwise there may be a conflict or the programmer may try to power-up everything else on your pcb. I use jumpers to do this, but you could use solder links if you don't plan to program the PIC again.

One other thing (if you are using the PICStart programmer): The PICStart programmer starts programming very soon after raising the power supply. If you put all the PIC decoupling capacitors on the programmer side of the isolation, the +5V may not settle in time, and the programming will fail. I normally put 1 capacitor on the pcb +5V supply side of the isolation, and 1 on the other side.

All the best
___________________________
This message was ported from CCS's old forum
Original Post ID: 8480

[PCM programmer]

:=:=I planned on using ISP to flash my pic16f374, but seem to be missing something. The clock has to be running for ISP to work, and yet I cannot get my crystal to run until the proper config bit is set (default= RC). On the prototype I can put an RC in until the first flash is complete, but don't want to do that in production. Is this a catch-22, or am I missing something?
:=:=
:=:=thanks.....
:=
:=You shouldn't need the OSC clock running during ISP. Just make sure that you have connected all the ISP signals - 0V, +5V, MCLR, PGC(RB6), and PGD(RB7).
:=
:=You will also need to isolate the rest of your pcb from the PIC signals used for programming. Otherwise there may be a conflict or the programmer may try to power-up everything else on your pcb. I use jumpers to do this, but you could use solder links if you don't plan to program the PIC again.
:=
:=One other thing (if you are using the PICStart programmer): The PICStart programmer starts programming very soon after raising the power supply. If you put all the PIC decoupling capacitors on the programmer side of the isolation, the +5V may not settle in time, and the programming will fail. I normally put 1 capacitor on the pcb +5V supply side of the isolation, and 1 on the other side.
-------------------------------------------------------
I have ICSP working on my current project with a 16F628.
I'm using a PicStart-Plus and High Voltage Programming mode.
I don't have +5v from the PicStart-Plus connected to the
16F628. The PIC gets the +5v from the project board's
power suply. It works OK. I just have to turn on power to
the board before I start programming it. (I did it this way
because I read that the PicStart-Plus has a very poor output
drive. I was concerned that it could not supply enough current
to power my board).

This would appear to be in violation of the timing diagram
shown in Microchip's ICSP appnote for the 16F628.
<a href="http://www.microchip.com/download/lit/suppdoc/specs/30034d.pdf" TARGET="_blank">http://www.microchip.com/download/lit/suppdoc/specs/30034d.pdf</a>
In Figure 2-2, they show that for HVP mode, Vpp must go high
before VDD. But I kept reading in various PicList articles
that it's Vpp going high that causes the PIC to enter HVP
mode. In other words, VDD can already be high, and it won't
hurt. So I tried it that way on my proto board, and it works
every time. (VDD goes high several seconds before Vpp, since
I'm turning it on with a switch).
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This message was ported from CCS's old forum
Original Post ID: 8503

[Bill Meyer]

The ICD-S User Manual, page #4, states that:

"The target chip oscillator must be running for the ICD-S to work".

I assumed that I couldn't flash if the ICD-S didn't work.



:=:=I planned on using ISP to flash my pic16f374, but seem to be missing something. The clock has to be running for ISP to work, and yet I cannot get my crystal to run until the proper config bit is set (default= RC). On the prototype I can put an RC in until the first flash is complete, but don't want to do that in production. Is this a catch-22, or am I missing something?
:=:=
:=:=thanks.....
:=
:=You shouldn't need the OSC clock running during ISP. Just make sure that you have connected all the ISP signals - 0V, +5V, MCLR, PGC(RB6), and PGD(RB7).
:=
:=You will also need to isolate the rest of your pcb from the PIC signals used for programming. Otherwise there may be a conflict or the programmer may try to power-up everything else on your pcb. I use jumpers to do this, but you could use solder links if you don't plan to program the PIC again.
:=
:=One other thing (if you are using the PICStart programmer): The PICStart programmer starts programming very soon after raising the power supply. If you put all the PIC decoupling capacitors on the programmer side of the isolation, the +5V may not settle in time, and the programming will fail. I normally put 1 capacitor on the pcb +5V supply side of the isolation, and 1 on the other side.
:=
:=All the best
___________________________
This message was ported from CCS's old forum
Original Post ID: 8513

[PCM programmer]

:=The ICD-S User Manual, page #4, states that:
:=
:="The target chip oscillator must be running for the ICD-S to work".
:=
:=I assumed that I couldn't flash if the ICD-S didn't work.
:=
----------------------------------------------------------
You're using ICD. I think both he and I thought
you meant ICSP. (In-circuit serial programming).
___________________________
This message was ported from CCS's old forum
Original Post ID: 8515