ATMEGA164 Schematic (JTAG)

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First design with an ATMEGA164 (need that second UART...).  Also my first design using JTAG (rather than simple ISP connection).  Given this rather basic schematic, are there any glaring errors/omissions?

 

Side note: I've read that the only connections required to get an FTDI USB chip to work on a USB-C interface is to put two pull-downs on the CC1/CC2 pins (5.1k each).  Does anyone have any experience actually doing this?  I am conservative (hence the USB-Micro connector in the design as a backup...).

 

Science is not consensus. Science is numbers.

Last Edited: Fri. Dec 28, 2018 - 04:19 AM
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You DON'T need the resistors on the JTAG pins, they are shown in the datasheet to indicate the maximum load on those pins if used for something else as well as JTAG.

And of course the pinout is looking at the top of the PCB.

 

Are you not going to use JTAG on the other 2  chips?

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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John,

 

Thanks for the rapid response (benefit of a global community - it is 2315 here).  I thought I had read there were pull-ups inside the ATMEL ICE, but wasn't sure...

 

I'm not sure I understand your other two points.  The package is the QFN -- what do you mean regarding "pinout is looking at the top of the PCB"?  Also, what other chips (for JTAG)?  To clarify, in the screenshot above, U6A and U6B are two schematic symbols for the same physical component.

 

Edit: I just realized I pasted the screenshot twice.  Will fix that in the original post.  Is that what you were referring to?

Science is not consensus. Science is numbers.

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"pinout is looking at the top of the PCB"

I mean the JTAG connector is looking from the top of the PCB.

U6A and U6B are two schematic symbols for the same physical component.

OK clear now.

it is 2315 here

It's almost 4pm here and around 40 degrees Celsius outside, a bit cooler in my workshop.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Ok - so assuming I draw the land pattern of the connector properly, the pinout of the JTAG connection looks correct for an Atmel ICE?

 

40C?  Pffft.  It's a nice balmy 53F (12C) here (about 25 degrees (F) warmer than average for early January). 

Science is not consensus. Science is numbers.

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pinout of the JTAG connection looks correct for an Atmel ICE?

Yes and for any other JTAG debugger like the older JTAG Mk2 and MK3 in case you still have any around.

 

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly