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General discussion / Re: just a little bit of fun...
It's inside a VHS tape...[/quote]
Isn't it rather VHS-C? :D (Sorry, couldn't resist)
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Messages - chr
It's inside a VHS tape...[/quote]
Isn't it rather VHS-C? :D (Sorry, couldn't resist)
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General discussion / Re: Cheap PCB manufacturing timelines
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For size reference - the oblong pad is 2.6x1mm.
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General discussion / Re: My christmas order arrives
Is this heat shrink tubing on both jaws of the alligator clips to keep them from scratching the pcbs?
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General discussion / Re: My christmas order arrives
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General discussion / Re: Sure Electronics PICkit 3
Yes, my case looks exactly like you describe it; the font for the "PICKIT" text was also changed. It matches the photo on their web store.
I suppose that hardware wise my device is identical to the ones you and Sjaak received. Could either of you check R36/R41? They are located to the left on the bottom side of the pcb. On mine these were 4k7/2k7 at the time I received the device (before modification).
If these are indeed the correct values then my next guess is that somewhere (maybe on the 25lc256) are calibration constants which are applied to the raw ADC values. If theses constants were wrong that would explain why I was getting wrong values.
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General discussion / Re: Sure Electronics PICkit 3
So do you get the correct target voltage displayed on the Status Page in the PICkit Settings dialog?
[quote author="ian"]May I post the entirety on the blog?[/quote]
Sure.
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General discussion / Sure Electronics PICkit 3
some time ago there was this blog post about the PICkit 2 clone. A few weeks ago I bought the PICkit 3 clone from the same manufacturer - here is my experience with it.
Until then my experience with PIC programmers was a homebuilt JDM serial programmer (about a decade ago...) and a loaned Microchip ICD 3 that I used for an uni project.
First impression
This clone is really cheap - I could get about two for the price of a single genuine Microchip PICkit 3. Nevertheless it comes in a sturdy box and includes both a single row 6-pin female to female and a 6-pin modular connector ICSP cable. There's also a 1x6 pin male header, a right-angle 1x6 female header and the Mini-USB cable included.
The case looks pretty much like the one in the blog post linked above; it seems reasonably sturdy and to open it you just have to slide your fingernails along the groove. The pcb is held in place by four thin plastic posts. To separate it from the upper shell you might have to push a bit on the leds from the outside - they sit very tight in their cut-outs.
Because of the black solder mask it's a bit hard to make out how much flux residue there's on the board. Especially on the bottom, around the pins of the buttons there was definitely residue. I encountered maybe one or two bits of stray solder but all in all I've seen worse. The socket you connect the programming cable to seems a bit weak; applying small pressure is enough to bend it upwards and maybe snap the pins if this happens too often. Although, with the case in place bending it upwards is not really possible.
Use
MPLAB v8 was already installed on my machine, so I just had to connect the clone and select it as a PICkit 3 programmer/debugger. At that time I had a board with a PIC24F nearby and sure enough, after MPLAB had finished downloading the appropriate firmware, almost everything worked as it should.
There was one bit that was bugging me. In MPLAB there's a dialog box for the PICkit where you can configure the Programmer-To-Go feature, enable power supply by programmer and monitor V[sub:]DD[/sub:] of the connected board. Well, the reported voltage was not correct. Instead it reported approx. V[sub:]DD[/sub:] x 2.2.
It seems that MPLAB actually doesn't care if the reported V[sub:]DD[/sub:] is too much for the selected device but if you use the programmer to supply power the reported V[sub:]DD[/sub:] can't be too much below the set value. If it is, MPLAB reports that it has recognized a short circuit on either V[sub:]DD[/sub:] or V[sub:]PP[/sub:].
Next, I tried the clone on an old PIC16 which needs about 13V V[sub:]IHH[/sub:] to enter programming mode. MPLAB informed me that it can only read 00000000 as device id, which isn't what it was expecting... Long story short - the programmer is only supplying about 6.1V V[sub:]pp[/sub:].
Contact with Sure Electronics
... was a bit difficult. In the package there was a small card with an email address on it in case there were any problems. After a few days of waiting and trying a different way of contact I managed to get a response.
I explained the problems I was experiencing and suggested that there might be a hardware problem with programmer but as answer I got sent some links I had already seen entering the MPLAB error message into Google. I also had to confirm a few times that I had indeed connected the ICSP correctly (an understandable question but I think one time is enough).
Next I was provided with a firmware file (I assume in case the PIC24 inside the clone had been corrupted) which I unfortunately couldn't try as I didn't have the ICD 3 anymore.
After that a suggestion for addition of an resistor to the PCB arrived but doing this changed neither the wrong V[sub:]DD[/sub:] display, nor the inability to generate a high enough V[sub:]PP[/sub:].
Fixes/Improvements
A schematic of the genuine PICkit 3 is provided in Microchip's DS51795 document. The clone does not deviate too much from this.
My first bet was a wrong reference voltage (VREF_2.5). It turned out to be alright.
Next, I backtracked my way from the ICSP connector to RB2, where V[sub:]DD[/sub:] is sensed. There's a voltage divider involved where VDD_FBACK originates. On the clone these two resistor had different values compared to the schematic but they did have the correct ratio. Tweaking this ratio quickly lead to a correct V[sub:]DD[/sub:] display in MPLAB.
The situation for V[sub:]PP[/sub:] is similar. It also has an associated voltage divider and careful changes combined with monitoring this voltage during the phase were MPLAB tries to read the device id got me where I wanted to be.
If you want the clone to supply power it also makes sense to modify the gain of the amplifier which is tasked with regulating VDD_INT; this was a bit off on my device.
The dual colour status LED was not working on it's green side, I'll also have to replace this one.
I'm not sure why these fixes were necessary in the first place although I can imagine a reason or two...
Conclusion
I still think that the price/performance ratio for this clone is not bad but if I knew that I had to invest a few hours looking for the cause of this defects, writing emails and questioning if the problem was maybe even PEBKAC on my end I would have bought the genuine product.
Email contact with Sure Electronics was not exactly what I hoped for - there was this initial delay and in the end I had to find a solution myself - but I do have to say that the person I was communication with was polite and relatively fast to answer (after communication was established).
I hope that some of you have already tried out either the Microchip PICkit 3 or a clone and can provide some insight. In particular I would like to know if you've encountered similar (or different) problems and if you stumbled upon any difference between the Microchip schematic and a genuine PICkit 3.
EDIT: The socket for the programming cable is indeed not very sturdy. It's pins just snapped.
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Project logs / Re: Free PCB Build - MCP2200 breakout
Here in Austria (AFAIK it's the same for Germany) both RS Components (Allied Electronics in the US) and Farnell (Newark) do not do business with private customers. According to their terms and conditions they will only accept orders from companies.
There were exceptions to this policy for students last time I checked.