04/11/2019 at 19:09 •
Hi, I decided to open Tindie store for selling some spare boards I have. They aren't populated, but I can make a few to order, just contact me. I don't have to solder them, I might as well sell them as DIY kit...
12/02/2018 at 16:07 •
This is how ready Xplained Yourself rev. 1.1.1b looks like:
It works great. I tested it with ATmega328P and ATtiny1616 as far. It can program and debug, no surprise here :)
I didn't have ferrite bead so I replaced it with piece of wire, also I didn;t have one 47u capacitor, so I replaced 1117's output cap with 1u ceramic one. I'll order them when I'll have more parts to buy.
I made few minor mistakes:
- LED name - is programming indicator not power. (I added power LED with it's resistor across C4)
- Few ground vias are not connected.
- No via is tinted.
- Few names are hidden beneath footprints.
I changed that in 1.1.1c. I also added some improvements:
- More ground fields for better screening signals.
- Power LED.
- Target voltage sensing LED.
- Test point for ATmega's reset (external programmer is needed to set clock out fuse, which is necessary for routing clock signal to CLKO pin).
- 5V protection Schottky diode. Schottky diodes have low drop - 0.3V. That means, output voltage is 4.7V, which is safe for 16MHZ and 20MHz AVRs, and should be enough.
- Signal names on silkscreen.
- I moved few traces I was afraid could touch others.
- Here are pictures of new board:
11/19/2018 at 17:32 •
I made semifinal version. It includes MOSFET level translators. (It might become final after successful tests)
I wanted to include integrated level translator, but they are expensive (MAX3002) or hard to find (GTL2003) or reported faulty (74245 with AVRISP mkII). There might be some conspiracy: none of the above have pinout compatible with another!
I chose BSS138 MOSFETs because I inspired myself with Sparkfun's level converter tutorial. I believe, that generic level converters, I have, have the same transistors (or something with worse parameters) and they work properly, so it's worth a shoot.
New board is bigger than 1.0, but still pretty small ~45x90mm (something like ~1.8"x3.6").
I ordered few PCBs from Chinese manufacturer. They should arrive this week, I'll test them ASAP.
Oh! The "b" in reversion means, that there was 1.1.1 in the process. In 1.1.1 I used autorouter, which did the job I wasn't satisfied with. Then I saved it with different name, rip up that mess and routed it manually.