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Re: Some questions met when designing PCBs

 by Piquan ¦  Sun Oct 14, 2018 3:58 am ¦  Forum: PCB Design Questions ¦  Topic: Some questions met when designing PCBs ¦  Replies: 4 ¦  Views: 1757

PS: Sorry to necro the thread; I hadn't checked the date!

Re: PCB Hole size to use with ISP Pogo Adapter

 by Piquan ¦  Sun Oct 14, 2018 3:57 am ¦  Forum: PCB Design Questions ¦  Topic: PCB Hole size to use with ISP Pogo Adapter ¦  Replies: 2 ¦  Views: 868

PS: Sorry to necro the thread; I hadn't checked the date!

Re: Some questions met when designing PCBs

 by Piquan ¦  Sun Oct 14, 2018 3:52 am ¦  Forum: PCB Design Questions ¦  Topic: Some questions met when designing PCBs ¦  Replies: 4 ¦  Views: 1757

One of the best articles I've read about this is from the June 2012 issue of "Analog Dialogue": http://www.analog.com/en/analog-dialogue/articles/staying-well-grounded.html . It's a good read, and whether you just give it a quick read-over or check each equation individually, it'll probably help. Th...

Re: PCB Hole size to use with ISP Pogo Adapter

 by Piquan ¦  Sun Oct 14, 2018 2:32 am ¦  Forum: PCB Design Questions ¦  Topic: PCB Hole size to use with ISP Pogo Adapter ¦  Replies: 2 ¦  Views: 868

Yes, it's for the 0.1" pitch 2x3 ICSP header footprint, just like the one on an Arduino. Pogo pins don't strictly need holes, although a hand-soldered pogo jig like this is easier to get lined up if you have them. Just stick with your usual via size; anywhere between 0.6-1.0mm works well (just testi...

Re: Cut power to TLC5940 => LEDs turn on

 by Piquan ¦  Sat Oct 13, 2018 9:58 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Cut power to TLC5940 => LEDs turn on ¦  Replies: 3 ¦  Views: 281

To turn on an LED, the TLC5940 pretends to be a ground connection. When you have Vcc connected, the logic can decide whether or not it wants to behave that way. When you have Vcc disconnected, it can't control what it does (because the logic isn't working right), but it can still pretend to be a gro...

Pocket AVR Programmer not 3.3V safe; 74AHC125 instead?

 by Piquan ¦  Mon Oct 01, 2018 1:25 am ¦  Forum: SparkFun Product Questions ¦  Topic: Pocket AVR Programmer not 3.3V safe; 74AHC125 instead? ¦  Replies: 0 ¦  Views: 210

I came across a recent surprising discovery: the Pocket AVR Programmer ( https://www.sparkfun.com/products/9825 ) doesn't seem to be safe for use with 3.3V devices. As I understand it, on other USBtinyISP-based programmers, the output buffer exists to allow 3.3V safety, but that doesn't seem to be t...