Too many things called Vcc on Rainbowduino

I’m trying to get my connect a Rainbowduino to a little board I made with a DS1307 real-time clock. I thought I could get everything I needed from the cascading connector (SDA, SCL, VCC, GND) but this doesn’t seem to be working.

One of the confusing things on these boards is that there a several different things all referred to as Vcc. We have the AVR’s Vcc, which is regulated down from the Vcc coming in on either the little white connector or the green terminal block. Then there’s the (switched) Vcc’s for the LED array. And then there’s this other Vcc on the cascading connector.

So what is the Vcc on the cascading connector for? Is it an input? When the Rainbowduino is powered up I seem to see about 0.9V on that pin.

It’ll make my little RTC board much uglier if I have to add a regulator and a flying lead to the green terminal block.

You can use any of the power ports in either direction. The terminal blocks are a perfect example of this: One side would be connected to your power source with the other used to cascade through a number of others

I know that I can get power out of the terminal block, but it’ll be a bit ugly having to add a regulator to my RTC board and a flying lead to the terminal block. I was hoping that I could get regulated power, ground and data from the cascading connector, but that seems to be input only.

You could hook up directly to the Rainbowduino’s onboard 5V regulator. The output is the middle pin of the AMS1117. It doesn’t go to any of the external pins as far as I can see though.