So it is similar fault than before.
Are the regulators hot?
They will shutdown, when too hot, and start again after cooling.

 

Current and temperature of MCU is ok?

 

Current and temperature of MCU is ok?

Hi J and T,
I switched it off for an hour then on, and it ran for 20 seconds, then flickered to a stop, so it does seem temperature related.
I can't feel any heat anywhere.
The current seems ok.
I've tried internal and XTL for oscillation, same. With the XTL, the oscilloscope shows it also starts then stops
Is it possibly anything to do with the interconnected PICs? Both PIC PORTs are set OUT, I'll change them to what they will eventually be (SPI) etc.
C

 

Set all ports to inputs, except the one driving LED and try flashing it. I see the two PICs SPIs are connected and if both are set as push-pull outputs they may get damaged.

 

Hi,
Ahem!
Nothing's working today.
While programming the 4620, I heard sizling (residue flux), now the XTL isn't running.

The 4431, has decided not to be programmable?

Plan of the day:
Put two PICs on an old board, and program them there first. I have one board where the SPI has to be connected via plug in wires, I'll use that (without the SPI ¦ ) )
C

 

Programming currents and voltages are too small to make sizzling sound on PCB.

 

Programming currents and voltages are too small to make sizzling sound on PCB.

Hi T,
Agreed, but I think the sizzling is because the PIC hasn't been programmed yet.

Update: Both PICs on the donor, ok. flashing no sizzling
C

 

Why do you have connection from PICKIT3 Vdd to PCB 3.3V?
Pickits Vdd is output and can't be connected to 3.3V of the PCB

 

You can during programming use PCB power supply or make supply from PICkit but not in same time.

 

You can during programming use PCB power supply or make supply from PICkit but not in same time.

If supply is from PICKIT then there are all of the loads which are connected to 3.3V regulators.
PICkit can supply only about 30mA.

 

If supply is from PICKIT then there are all of the loads which are connected to 3.3V regulators.
PICkit can supply only about 30mA.

Hi J and T,
It normally programs ok.
Pickit3 is powered externally.

Note: With all this sizzling and errors, I'm ordering some more 18LF4620. At £6 each, I had better get a safer system!
C

 

Hi J and T,
It normally programs ok.
Pickit3 is powered externally.

Note: With all this sizzling and errors, I'm ordering some more 18LF4620. At £6 each, I had better get a safer system!
C

Is your 3.3V reg up and PICkit Vdd output off ( selected off in the program) when flashing the chips?

 

Is your 3.3V reg up and PICkit Vdd output off ( selected off in the program) when flashing the chips?

Hi J,
Yes, it's off in the programmer, and if I try to program without the PCB voltage ON, then it errors and lets me know.
C

 

Hi J,
Yes, it's off in the programmer, and if I try to program without the PCB voltage ON, then it errors and lets me know.
C

Why do you have then connection from programmers Vdd to 3.3V

 

Why do you have then connection from programmers Vdd to 3.3V

Hi J,
Isn't that how it should be wired?
How do you think it should be wired?
C

 

My bad.

Hi J,
Isn't that how it should be wired?
How do you think it should be wired?
C

My bad
I was confused that the Vdd on Pickit is output only and could by accident be on at the same time as the Vdd on PCB.

 

MPLAB programmer usually warns if PICkit power delivery is activated. If high voltage programming is in use then voltage sensitive components connected to MCLR must be temporarily disconnected. Look at the poster which comes with the PICkit3.

 

My bad.

My bad
I was confused that the Vdd on Pickit is output only and could by accident be on at the same time as the Vdd on PCB.

Hi J,
That's fine.
Thanks for your detailed checking.
C

 

MPLAB programmer usually warns if PICkit power delivery is activated. If high voltage programming is in use then voltage sensitive components connected to MCLR must be temporarily disconnected. Look at the poster which comes with the PICkit3.

Hi T,
I hope I'm using it correctly, thanks.
C.

 

Hi,
I've searched the likely outlets, for 18LF4620-I/PT PIC, but there don't seem to be any in stock at all.
I did find a Russian site, but I didn't order, and French ebay has some. UK Ebay, also has some but £10 is too much for me to 'pop' in no time.

An obeservation: First I added 1x PIC to the board, and problems only arrived when I added the second one, this happened at all times, so I think the problem muxt be interconnections between the PICs.

I have one 18LF4620 left on an old working PCB, so I may program it, then, cut the tracks on PCB7 and see what happens.

Note: Microchip offer to program Pics, before posting them! This is a possibility.
C.