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PSoC 4

Anonymous
Not applicable

I have a new board design using the CY8C4014LQI-422 24-pin QFN. We built a few dozen boards and I'm unable to get the MiniProg3 to communicate with any of them. I noticed that I had VCCD connected to VDD (the datasheet on page 7 calls pin 6 VCC rather than VCCD - it's easy to assume this is just another power pin so it might be a good correction to make in the datasheet). I also left the big center pad floating rather than grounded. I plan to change these issues in the next board spin but I made these changes on a couple boards and they still won't communicate. I'm hoping an expert might look at my schematic/layout and see something obvious that I missed (other than the VCCD issue). I've tried powering the board externally and via the programmer, and at many different clock speeds to no avail. It seems to me that there is no 1.8V output on the VCCD pin -  I thought I replaced the part with a new one when I did the rework. If not, could the part have been damaged by the previous faulty power scheme?

I've developed with PSoC4 parts on several designs in the past and haven't encountered this so I'm at a bit of a loss. I'd rather not post my design files here so if someone does have the ability to look at it, let me know and I can send them.

Thanks.

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1 Solution
Anonymous
Not applicable

With the assistance of my extremely helpful FAE from IRI, we were able to resolve the issue. Apparently this particular part has a temporary POR during power-up on pin 1.6. My design has a pull-up resistor on this line as well as a switch to ground, which arrives in the closed position, grounding this pin. When I opened the switch, the part started communicating with the programmer like magic. I would have burned a lot more days trying to figure this out, so I hope this can help someone else out in the future. I would suggest to Cypress that this might be a good thing to document in the datasheet.

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6 Replies
Anonymous
Not applicable

I'm adding the relevant portion of the schematic in hopes that it may lead someone to an idea for a resolution in a more timely fashion. Thanks.

PSoC.jpg

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DaBr_1233126
Contributor

So did you put a cap from Pin 6 to ground?   I've made this same mistake a time or two and chip did survive.  But that doesn't mean that yours did.  Only other thing I can think of is a pull up resistor on the reset line.

If the design files are in Eagle, I will look at them.

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Anonymous
Not applicable

The design files are in Orcad Allegro. I made sure there was a 1uF cap on VCCD after fixing my mistake. Since my original post, I also tried having the programmer supply 1.8V when programming on some of the virgin boards (ones that haven't been powered up previously) and same thing. I should be able to at least program the board using a 1.8V supply with VCCD and VDD connected, correct?

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Anonymous
Not applicable

Perhaps, try removing the capacitor from XRES? The chip should have an internal pullup on the XRES allowing you to get rid of the capacitor from your BOM at the very least.

Try putting caps from VCC and VDD to ground. (VCCD and VDD only need to be separate if your power supply is not externally regulated)

(probably not a big issue )

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Anonymous
Not applicable

With the assistance of my extremely helpful FAE from IRI, we were able to resolve the issue. Apparently this particular part has a temporary POR during power-up on pin 1.6. My design has a pull-up resistor on this line as well as a switch to ground, which arrives in the closed position, grounding this pin. When I opened the switch, the part started communicating with the programmer like magic. I would have burned a lot more days trying to figure this out, so I hope this can help someone else out in the future. I would suggest to Cypress that this might be a good thing to document in the datasheet.

View solution in original post

Anonymous
Not applicable

I would suggest marking your post as the answer

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