Problem with Inchworm Plus

[Ambient]

Hey guys, I finally got around to programming a PIC again, and need some help. I was wondering if anyone had an Inchworm Plus could verify their VPP voltage for me. In MPLAB it tells me the ICD 2's VPP is ~12V, while at the PIC I am measuring -4V, sometimes 7V, once it was 5V...sigh.. I am thinking my programmer is damaged (or wrong setting) and was wondering if someone has seen this before. Unfortunately I need to get this PIC programmed by Sat, as it is going into a motorcycle light controller for a parade this weekend!

Here are the errors I get:

Connecting to MPLAB ICD 2
...Connected
Setting Vdd source to MPLAB ICD 2
Target Device PIC12F683 found, revision = Rev 0x3
...Reading ICD Product ID
Running ICD Self Test
...Passed
MPLAB ICD 2 Ready
Erasing Target Device...
ICD0152: Failed to read all of requested bytes (0x0 of 0x8)
...Erase Failed
ICD0152: Failed to read all of requested bytes (0x0 of 0x2)
ICD0082: Failed MPLAB ICD 2 operation

It also seems to read just fine. Is it safe to simply use my power supply to get 12V to VPP and bypass the Inchworm?

COM1 settings: FIFO, bps = 57600, data bits = 8, no parity, 1 stop bit, no flow control.

Thanks so much for any help!

 

[Ambient]

It also won't load the ICD2 OS as well...

 

[blueroomelectronics]

Check for 11V or more on the VPP jumper.

What value MCLR pullup on your 12F683?

 

[Ambient]

Actually it might be just a plain inchworm, revE. I don't see a jumper. The VPP test point on D6 shows 12v, and I am getting 12V on MCLR now, but it is still coming up with the same errors. I have tried it on an old project that I know works fine, and same result. I am also wondering why it won't program the Inchworms pic (ICD08010500.hex).

Still the same errors. Could it be some setting in MPLAB? It has been a while but I don't remember ever having this problem.

Right now I just have the pic on a breadboard, no pullups or other passives/actives. The programmer is told by MP LAB to power the target device.

 

[blueroomelectronics]

Try a 22k resistor pullup on the targets MCLR

 

[Ambient]

Put a 22k from MCLR to VDD, it works! So why do I need to do this all of a sudden? I also tried one of my old projects and had the same problem, which I never did before! I am using all the same hardware. I thought MCLR was on my default with an internal weak pullup. I will have to add a pullup to the final project also I guess.

Thanks so much for the help Blue! I am thinking about getting the Junebug soon so I can program with my laptop. You have great stuff!

 

[blueroomelectronics]

Unless you turn MCLR into an input pin it needs to be pulled high by an external resistor. If you use both the internal MCLR & internal OSC the non VPP before VDD original inchworm may have a problem getting into program mode.

I wish Microchip would put a weak pullup enable on MCLR, after all they put everything but the kitchen sink inside some PICs.

Glad you're enjoying the kits.

 

[Ambient]

OH, I thought there was an automatic weak pullup if MCLR was on. I will have to read the spec sheet again... I was intending on using GP3 for a digital input, so I will have to look into it more. But the project works for my minimum requirements as is for now.

 

[blueroomelectronics]

Ages ago I put a reed relay & flyback diode on my original Inchworm (pin RA4) to act as VDD control. The Inchworm+ uses a simple BS250K for the same purpose.

If you use both MCLRE OFF and INTERNAL OSC you'll need that feature to get it into programming mode (else the PIC has made MCLR an input pin before the programmer can get control)