There is a nice workaround to still get debug output: An additional serial to USB bridge. http://www.ebay.de/itm/FTDI-FT232RL-USB-to-TTL-Serial-Converter-Adapter-Module-5V-and-3-3V-For-Arduino-/253088745709 The IC always uses 5V on the USB side and lets you set the serial level (3.3V or 5.0V. Some ...

I don't know how the IOREF pin is supposed to be used but I really recommend not using it for power. You are right, I misunderstood the docs about IOREF. I thought it's a reference signal that sets the logic level of the Arduino but it is the other way around and tells external hardware what the Ar...

When I use the Arduino for debugging, it is powered from USB. Even when not connected to USB, the makers of the Arduino board say "Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it." (https://store.arduino.cc/usa/arduino-uno-rev...

You are using 3.3V for power, right? That was it! I did not think about this because it worked fine with the SCPH-5502 (but maybe injecting at 5V destroyed the protection diode on the chip and bricked it). Now I connected the device's 3v3 to the Arduino's IOREF and it worked on the first try. This ...

With a PU-22 in a SCPH-7502 and an Arduino Uno I am getting strange readings on the SUBQ signal. The SQCK seems to be fine, at least it looks like some sort of clock signal. Logging it to the serial console, it changes about every 40-50 lines (I guess the logging itself affects the number of Arduino...