Glove Load Current Draw Estimation

[digitaldanny]

Describe the solution you'd like Collect the expected current draw from each hardware component and calculate the total expected draw from the battery in the worst case.

[digitaldanny]

Updating this comment as I find power draw for each item.

• MSP432
  • Active mode = 80uA/MHz. I believe this means that there will be 80*48uA = 3.84 mA.
  • There are a few low power modes that offer between 25 - 660 nA for all clock speeds. If I use one of these low power modes, I might be able to drop down the current draw average.
• 64x48 OLED LCD
  • Typical 15 mA
  • High 30 mA
• HC-05 Serial to Bluetooth Module
  • Active 35 mA
  • Sleeping <1mA
• Flex sensor circuitry
  • Flex sensor voltage divider: Assuming the uC pulls 0 current and the flex sensors are an average of (225 + 12k)/2 ~= 6k, the current draw for each voltage divider is I = 3.3/(22k + 22k + 6k) = 66 uA.
  • CD4051BE Analog Demux: Input current is negligible for each input no matter the voltage level.
  • LM324 Amplifier: Max output current aroudn 40 mA, but the actually current draw depends on the 10 Hz LPF following this amplifier.
• MPU-9250 Accel/Gyro/Mag
  • Gyro - Active 3.2 mA, sleeping 8 uA
  • Accelerometer - Active 450 uA, sleeping 8 uA
  • Overall ~3.5 mA with all 6 axes and DMP enabled
• TPS63020 Buck/Boost Converter
  • Quiescent current = 25 - 30 uA
  • 100 mA efficiency ~= 93% will act as a multiplier for all components powered by this IC

[digitaldanny]

Low-Power mode

MSP432 LPM + TPS63020 Quiescent = (25 + 660 nA)/2 + (25 + 30 uA)/2 = ~28 uA.

Fully active circuit

(MSP432 Active + OLED Typical + HC-05 Avg + Flex sensor circuits + MPU6500 Overall Active) / Power Efficiency = (3.84 mA + 15 mA + ~17 mA + ~20 mA + 3.5 mA) / 0.93 = 63 mA