SLAAEF6 September   2023 MSPM0L1105 , MSPM0L1106 , MSPM0L1306 , MSPM0L1344 , MSPM0L1345 , MSPM0L1346

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1PIR Design Description
    1. 1.1 PIR Sensor
    2. 1.2 PIR Signal Chain
      1. 1.2.1 Traditional Motion Detection Signal Chain Design
      2. 1.2.2 Capacitor-Free Signal Chain Design
  5. 2Hardware and Schematic
    1. 2.1 MSPM0L1306
    2. 2.2 MSPM0 PIR Boosterpack
      1. 2.2.1 Schematic
  6. 3Software
    1. 3.1 Software Architecture
    2. 3.2 Software Flow Chart
    3. 3.3 Data Processing
      1. 3.3.1 Digital Signal Conditioning
      2. 3.3.2 Low-Pass Filter for Temperature Drift
      3. 3.3.3 Spikes and Noise
      4. 3.3.4 Motion Detection Function
  7. 4Results
    1. 4.1 Power Profile and Current Consumption
    2. 4.2 Detection Performance
      1. 4.2.1 Distance: 5 meters (16.4 ft)
      2. 4.2.2 Distance: 9 meters (29.5 ft)
      3. 4.2.3 Distance: 10 meters (32.8 ft)
  8. 5Summary
  9. 6References

4.1 Power Profile and Current Consumption

The software flow is what ultimately controls the system's power profile. Figure 4-1 shows some timing and signal captures on an oscilloscope and has been annotated to explain where you are in the software flowchart. It takes ~90 μs to wake-up from Standby, enable the analog, wait for it and the measurement signal to stabilize, and complete the ADC conversations. The Blue trace is the output of the PWM DAC needed on the MSPM0L13xx solution and discussed in Section 1.2. The yellow trace is our measurement signal from the end of the PIR signal chain and you can see it stabilize right as the ADC conversation starts. After the measurement, the analog is shut off and the data processing is done. Then the MCU goes to Standby for ~50 ms.

Ultimately, this solution has been measured to average ~12 μA when running at 20 SPS. This power measurement includes the MSPM0L1306, the integrated signal chain, and also the power for the PIR sensor.

GUID-048C1039-777F-4032-8454-2AB2ABF66310-low.png Figure 4-1 Power Profile of MSPM0L13xx PIR Demo Software