Took me a minute to figure that one out, but I think I will just throw a few more diodes in to protect this from happening. Enough to power on the LED on the motherboard with no other ICs plugged in. The net result is that leakage was happening backwards through these resistors when the data/clock lines were high. I did this on purpose as I didn't want to pull these lines high while programming the microcontroller, but need to pull them high for I2C. The less easy to spot issue is that I used the stand-by power to power the microcontroller, but I put pull-up resistors on the I2C lines (and SPI programming lines) to the system voltage and not the VSB.
![prototype 3 not happening prototype 3 not happening](https://blog.holbertonschool.com/wp-content/uploads/2020/07/image-6.png)
One is just cosmetic, and the other is a bodge job on a chip which I will admit, is next to impossible to see in this photo. Two of my mistakes are visible in the pic, see if you can find them. Of course, I'm pretty much going to make a mistake somewhere on a board of this size, and this time is no exception! Fortunately, they were easy to spot and the actual logic is working as it should. This turned out to be pretty easy now that the I2C header will also work as an Atmel ISP programming header.
![prototype 3 not happening prototype 3 not happening](https://3.bp.blogspot.com/-8i1PEAitoTE/VXXjmVuWZGI/AAAAAAAAAWc/FuBqMkzUmU0/s1600/prototype2.jpg)
#PROTOTYPE 3 NOT HAPPENING CODE#
I had to get my code moved over to the ATTiny861 before the board would even power on. I received the parts for the third Prototype on Tuesday evening and spent a good chunk of that night and a bit of yesterday morning getting it worked out.