Junebug Prob again!

Hi 3V0 you hit the jackpot and i got my very own PICkit2. Thanks a lot.

To Blueroom Thanks for every thing.I got my PICKIT2 finally working.

Sarma Thank you for taking the time to reply to my post. I will post another one very soon.

Now since i got it working it is not detecting the 16F628A i connected with it on a solderless breadboard.Heres how i made the connctions:

Vpp=4
Gnd=5
PGD=13
PGC=12
5v=14

Wond3rboy said:

Now since i got it working it is not detecting the 16F628A i connected with it on a solderless breadboard.Heres how i made the connctions:

Vpp=4
Gnd=5
PGD=13
PGC=12
5v=14

Click to expand...

That looks right to me.

Use the PICkit2 trouble shooting tool to check signals and voltages. The tool explains itself.

I am using the ICD pins k.All other are confirm but pin number 3 of 18F2550 is T_FB. I have taken it as Vdd.

Can the inductors be causing a problem since i am using 3 200uh ceramic inductors whose saturation current i dont know.It was said only after i had already soldered them in that saturation current could cause the inductance to significantly decrease.

A short was detected on Vdd.And the trouble shooting can not continue.

With out any thing connected:

It said that that an external voltage was connected to Vdd at 4.1v.

Low Vpp detected 4.3v and it can not supply more than a few ma.

And no voltage on PGC or PGd.

Wond3rboy said:

To Blueroom Thanks for every thing.I got my PICKIT2 finally working.

Click to expand...

Perhaps you should clear Bluerooms good name by restating that this was not a Junebug problem as stated in your title

Well nice but a thanks does not hurt.Any ways here is a Junebug CLONE problem.Now when i start the PICKIT2 software it says Vpp voltage level error so i guess that is an inductor problem.Right?

I have got three more such inductors but no LC meter.I can connect more of them though.


PS: I wouldnt mind it if the Mods changed the name of the post to Junebug CLONE Prob again!

Mikebits said:

Perhaps you should clear Bluerooms good name by restating that this was not a Junebug problem as stated in your title

Click to expand...

one can put a title, but can't change. Thus Junebug remains and Bill has to face it. Perhaps one has to be mindful while scribing a title.

wond3rboy must be trying his own version of Pickit2.

Wond3rboy said:

Hi Sarma this is how i connected the 18F2550 using the communication config with the 7805.I left the DATA pins as they are and connected the +5v to the 7805 i/p.

Click to expand...

Perhaps you need to use close up while taking this Photo and the minimum distance to be maintained for clarity/ but it could be edited before posting so that one could see with clarity, that was lacking in your photo. Do little practice and get good snaps!!!

mvs sarma said:

one can put a title, but can't change. Thus Junebug remains and Bill has to face it. Perhaps one has to be mindful while scribing a title.

wond3rboy must be trying his own version of Pickit2.

Click to expand...

I am trying to clone the Junebug and working very hard to make it work since most of the components were /are not available here.

Hello Wond3rboy.I have met all the errors you get.I did my very best methods to overcome that "Vpp & VDD level errors" but I couldn't.

The problem with my PC power supply is too low.VDD is below 4.5V & after boosting VPP=10.7V that is too low.

For Vdd errors-
Only solution is to give external VDD to your target board for VDD errors.

For Vpp errors-
Isolate VUSB from the PC & supply seperate 5V power to the whole junebug.

Wond3rboy said:

I am trying to clone the Junebug and working very hard to make it work since most of the components were /are not available here.

Click to expand...

Even I do not have BS250 & I put an alternative.DId you make the complete junebug?

I made the Clone seperately for the tutor and the Junebug Programmer. The tutor PCB is etched but i am waiting for the components to arrive.I have been improving it though. If you want it then i can give it.The thing is that there is no one i know in
Pakistan that has the PICKIT2 since no body in the market knows about it(Karachi which is the biggest city here).I had to import a lot of things and had to pay USD 15 for my
18F2550. Learned every thing from the forum.

I tok a leaf out of your PCB may be thats why i am having the same problems although i did change the layout a lot i-e dont need to use any jumpers.Changed some resistor combinations.Followed the schematic basically but took a hint for the resistors on the bottom left out of your PCB(hope you are ok with it?).

By the way my PC power supply is too much.Last time i checked it while trouble shooting previously and found it to be 6.5 v.

Gayan Soyza said:

Hello Wond3rboy.I have met all the errors you get.I did my very best methods to overcome that "Vpp & VDD level errors" but I couldn't.

The problem with my PC power supply is too low.VDD is below 4.5V & after boosting VPP=10.7V that is too low.

For Vdd errors-
Only solution is to give external VDD to your target board for VDD errors.

For Vpp errors-
Isolate VUSB from the PC & supply seperate 5V power to the whole junebug.

Click to expand...

so if i am to get you correctly i disconnect VUSB from the Junebug,keep the other three pins and give the same 5v to the target chip?

Gayan Soyza said:

Hello Wond3rboy.I have met all the errors you get.I did my very best methods to overcome that "Vpp & VDD level errors" but I couldn't.

The problem with my PC power supply is too low.VDD is below 4.5V & after boosting VPP=10.7V that is too low.

For Vdd errors-
Only solution is to give external VDD to your target board for VDD errors.

For Vpp errors-
Isolate VUSB from the PC & supply separate 5V power to the whole junebug.

Click to expand...

What happened to the buffered usb mod we were thinking of?

Hi Sarma, the buffered mod was for the communication part of the programmer on a solderless breadboard. When i corrected the USB connections i thought i didnt need them since it was detecting it like all USB devices which work fine on the same port.If that is causing probs then i can add it easily since i dont have a board cutter my board has about an inch of space on all sides.Thanks.

mvs sarma said:

What happened to the buffered usb mod we were thinking of?

Click to expand...

As I recall the VUSB was too close to +5 for 78L05 to work. He would need a LDO (Low Drop Out) regulator whic is most posssibly another part he can not get. If you want to use a 5V regulator I suggest you use it with an aprox 9V power source, be sure to use caps as suggested in the datasheet. If you can get a 5V LDO regulator that would work. I like the LM2931AZ5 which has a dropout of .2V at 10mA. It can be had in .1 and .6 amp versions.
The nice thing is that this part will deliver 4.8V with an input of 5V. A lot of (most) regulators will not do that.

I agree with mvs sarma that you need to have a VUSB close to 5V. Without that everythis else is suspect.

This is my understanding of how the charge pump works. If I am wrong I would like to be corrected

The 18F2550 works between 2 and 6 volts, the extra half volt if it exits may not be a problem for the uC. But it may cause VDD to be too high.

The first thing to check for with a VPP short is the transistor connected to the inductor. It will not work if it is installed backward. I my case the datasheet supplied by the place that sold the transistor was wrong. You need to check it with a meter.

The PIC provides pulses on the VPP_PUMP pin. This causes the voltage in the inductor spike/jump above VDD each time a pulse happens. The diode D1 acts as a valve to charge the capacitor C1 with the + side of the pulse.

The PIC reads the voltage on pin VPP_FB (VPP_FeedBack( via the voltage divider formed by R6 and R3B. I do not recall what divider voltage maps to VPP 12V.

If the PIC see too little voltage on VPP_FB it causes VPP_PUMP to increase in frequency. When it see to little voltage it lowes the frequency. If it can not get the voltage to 12V it reports a short. The reporting of a short is misleading in that anything that prevents 12V will be called a short.

Check resistors R6 and R3B. If they are wrong VPP_FB will see the wrong voltage when 12V is right.

Check the direction of D1. If it is backward C1 can not charge.

I have been thinking about disabling the charge pump and placing 12V on the wire between R3B and the cathod of D1. If the voltage divider is working it should report a VPP of 12V. If VUSB is too high (6.5V) the internal voltage referance used by VPP_FB will be off. ....

Enough for now.

3v0

If I were to handle external power for the usb supported PICKIT2 or a clone, I would use the incoming power to operate the diode of opto isolator. This would indicate the PC that USB device has been plugged in. The transistor at the output would help me switch 9 or 12V DC as external input to a 5V regulator that would supply my board. If needed i would have another medium power transistor as buffer.

the entire set up would help me like externally powered USB.

Hi sorry to reply late but i was working on the 7805 module. I got the USB port thing sorted out and now i get 4.89V on my USB.Before actually using the mod i want to know whether the Vpp error solution that Gayan gave will work when inductance is low. The other 'prob' i found was that the capacitor C1 is rated at 6.3v not 25V as said in the specs. Is the capacitor causing a problem? If the 7805 mod can solve both the problems then i have it ready as well.Thanks.

When i start pickit2 programmer application i get this error "Pickit2 VPP Voltage Level Error Check target and retry operation".

The VPP errors that i found in other posts here were due to inductance thats why i am asking.

I am still getting the same errors!