MEP EP#338: Feature Complete or Minimal Viable Products
Project DiffProbe
- Landed on the topology Stephen wants
- High voltage dividers
- Compensation capacitors
- CMRR calibration (120dB rejection)
- Offset correction
- Buffers and Instrumentation Amplifiers
- Differential Stage
- 10x and 100x attenuation means offsets have to be bang on
- Opamps (3 of them)
- Buffers
- Low input bias current
- Low offset
- Bandwidth?
- Differential amp
- Low offset. Capable of driving 50 ohm load to the scope
- Gain setting resistors
- Vishay ACAS 0612 - Precision resistor network
- 4x0603 resistors to make a diff amplifier with a gain of 2
- Relative tolerance of 0.05%
- Worst case relative temp-coefficient 15ppm
Project Snackey
- Firmware is “feature complete”
- Display Commands
- How the vending motors actually work
- INA219 Current Sensor
- Interrupts
- Improved method for next revision?
- The one byte Serial Buffer problem
- NEOPIXEL (WS2812) vs APA102 (SK9822)
- Blocking functions
- DMA - Direct memory access
- Importance of full system integration testing
- Timer Lockouts for motors