Figure one shows the idea in a physical mock up. Actually, the parts are real, they just haven’t been soldered together yet. So, we have a battery bank of three Imedion NiMH “AA” cells, running between 3 and 4.2 volts and feeding a booster which supplies 5.0 VDC to the development board. We have the Photon (of course), and an ADC board (or other board) for sensor measurements. Did I mention that the Photon, in addition to WiFi, does I2C (1), I2S (1), SPI (2), ADC (8), DAC (2), UART (2), PWM and multiple general GPIO? For $19 bucks?
Figure 1: The simple connection from the USBIO to the ADC
The ADC devices currently in all three of my “homemade” tablets are a little under powered, so we’re upgrading all of them to use 16 bit Microchip MCP3426 ADC chips. The smallest reasonably hand solderable chip package is the SOIC. Most of the newest, fastest most glam chips are not even available with old-time DIP packages anymore. This is seriously bad news for oldish guys like myself.