I am integrating my Core with NightShade’s EnergyShield. The EnergyShield is basically an arduino style piggy back board that has a small LiPo and a fuels guage. When I use the Core and the EnergyShield without the SHield Shield, I have great success. I hook up the I2C plus a GND and it works great. Now I have a Shield Shield so I can put it all together in a nice connected bundle. The problem is getting I2C to work in this fashion. The Shield Shield moves Core D0 and D1 to Shield Shield’s D3 and D5 respectively. The Shield Shield also uses a bi-directional logic level shifter to make them 5V IO. So, I assume the I2C is now running at 5V on the Shield Shield’s D3 and D5. In this configuration, I am having no joy making the two devices communicate. I know there are varying schools of thought on if I2C can tolerate the 3.3v vs 5v difference… it does not appear to in this case. I went so far as to wire up a bi-direciton logic level converter to bridge the 3.3/5 gap. No luck.
I am also noticing that while the Core is running and breathing Cyan, it will periodically give about 10 rapid flashes followed by 5 very rapid flashed. Anybody know what this means?
All thoughts welcome.