3.1.5 Power Measurement

The board features an embedded power measurement device, the PAC1934, used for measuring the power consumption of the main power rails related to the MPU and peripherals.

The PAC1934 is a four-channel power/energy monitor with a current sensor amplifier and bus voltage monitors that feed high-resolution ADCs. Digital circuitry performs power calculations and energy accumulation. The PAC1934 enables energy monitoring with integration periods from 1 millisecond up to 36 hours. Bus voltage, sense resistor voltage, and accumulated proportional power are stored in registers for retrieval by the system host or embedded controller. For more information, refer to www.microchip.com/en-us/product/pac1934.

Four power rails are monitored: VDD_3V3, VDDIODDR, VDDCORE, VDDCPU. Each rail has a 0.047-Ohm shunt resistor for current measurement.

Figure 3-8. Power Measurement Schematic

The board features two options for retrieving data:

  • On-board USB-to-I²C bridge to access data with an external computer
  • Host SAMA7D6 Series MPU to access the data via a local TWI bus

A set of jumpers is used to manually select between the two access modes, on headers J6 and J7.

By default, the USB-to-I²C bridge is selected.

For more details concerning the USB-to-I²C bridge, see USB-to-I²C bridge.