The Scanalog 2 is a great inexpensive tool for hobbyists looking to debug digital issues, especially if they can't afford an oscilloscope. Debug SPI, I2C, Serial UART, 1-Wire, Maple Bus (more to come with software updates). You can even inspect that PWM or RC servo signal to make sure your arduino is outputting what you think it should.
- 20Msps on 4 channels
- 1.8V - 5V level detection
- 256k samples of storage on each line
- Playback on all 4 lines, or just 2 while reading from other 2
- Better Triggering
- More flexible output--static pwm to control RC servos, for instance, or just for a clock generator.