SLVUDH7 December   2025

 

  1.   1
  2. 1Description
  3. 2Features
  4. 3Applications
  5.   5
  6. 4Evaluation Module Overview
    1. 4.1 Introduction
    2. 4.2 Kit Contents
    3. 4.3 SNSR-DUAL-ADC-EVM Specifications
    4. 4.4 Device Information
    5. 4.5 Getting Started With the SNSR-DUAL-ADC-EVM
  7. 5Hardware
    1. 5.1  Hardware Overview
    2. 5.2  Power Requirements
    3. 5.3  ADC Connections and Decoupling
    4. 5.4  Analog Inputs
      1. 5.4.1 ADC1 Analog Inputs
      2. 5.4.2 ADC2 Analog Inputs
    5. 5.5  Excitation Connections and Low Side Bridge Switch
    6. 5.6  Analog Sensor Connections
      1. 5.6.1 Pressure Sensor (Resistive Bridge) Application Examples
        1. 5.6.1.1 Measuring a Voltage-Excited 6-wire Bridge Using ADC1 and a Low-side Bias Resistor Using ADC2
        2. 5.6.1.2 Measuring a Voltage-Excited 6-wire Bridge Using ADC1 and a Current-Excited 2-wire RTD Using ADC2
        3. 5.6.1.3 Measuring a Current-Excited 4-wire Bridge Using ADC1 and a Voltage-Excited Thermistor Using ADC2
      2. 5.6.2 Temperature Sensor Application Examples
        1. 5.6.2.1 Measuring a Thermocouple Using ADC1 and an NTC for Cold-Junction-Compensation Using ADC2
        2. 5.6.2.2 Measuring One 3-wire RTD Using ADC1 and One 3-wire RTD Using ADC2
        3. 5.6.2.3 Measuring One 4-wire RTD Using ADC1 and One 4-wire RTD Using ADC2
      3. 5.6.3 General Purpose Application Examples
        1. 5.6.3.1 Measuring Generic Voltage or Current Inputs
    7. 5.7  MSPM0G1507
    8. 5.8  Digital Interfaces
    9. 5.9  Digital Connection Headers
    10. 5.10 Shift Register
    11. 5.11 Connecting External Output Boards to Header J2
  8. 6Software
    1. 6.1 Top Level Menu
      1. 6.1.1 Top-level Help Menu Terminal
    2. 6.2 System Sub Menu
      1. 6.2.1 SYS Help Menu Output
    3. 6.3 ADC Sub Menu
      1. 6.3.1 ADC Help Menu Output
      2. 6.3.2 adc help Menu Input and Output Examples
        1. 6.3.2.1 adc reset Example
        2. 6.3.2.2 adc wreg Daisy-Chain Example (Writing to a Single ADC )
        3. 6.3.2.3 adc wreg Daisy-Chain Example (Writing to Both ADCs)
        4. 6.3.2.4 adc rreg Daisy-Chain Example
        5. 6.3.2.5 adc stream Example
        6. 6.3.2.6 adc lowpwr Example
  9. 7Hardware Design Files
    1. 7.1 Schematics
    2. 7.2 PCB Layout
    3. 7.3 Bill of Materials
  10. 8Compliance Information
  11. 9References

6.3.2.6 adc lowpwr Example

Use the adc lowpwr command to collect periodic sensor readings while minimizing power consumption. The firmware minimizes power consumption by cycling the MCU, both ADCs, and the bridge power between conversions. Figure 6-17 shows the timing diagram for the adc lowpwr command including the bridge power, ADC power, and the MCU power during one complete sensor cycle period.

ADS122S14EVM adc lowpwr Example Timing DiagramFigure 6-17 adc lowpwr Example Timing Diagram

As Figure 6-17 shows, the system on-time is effectively the sum of the ADC start up, ADC delay, and ADC conversion times, though the MCU must stay active slightly longer to process the received data and put the ADC in powerdown mode. The user must verify that the selected ADC settings result in an on-time that is less than the sensor cycle period. Figure 6-18 shows an example of the proper terminal syntax and response to get one reading from ADC1 and ADC2 every 1000ms: adc lowpwr 1000.

Syntax: adc lowpwr [sensor cycle period]

ADS122S14EVM adc lowpwr 1000 Terminal Input ExampleFigure 6-18 adc lowpwr 1000 Terminal Input Example

The firmware uses the current ADC settings set by the user to derive timing parameters and execute the adc lowpwr command. This command displays the applicable, user-configured ADC settings and derived timing parameters for reference. Table 6-2 shows the output from the adc lowpwr command.

Table 6-2 adc lowpwr Response
Parameter DescriptionTypeApplicable ADS122S14 Register
MODECurrent ADC speed modeUser ConfiguredDEVICE_CFG (0x05h)
f_MODMODE modulator frequencyResponseN/A
OSROSR register bitsUser ConfiguredDATA_RATE_CFG (0x06h)
START UPADC START UP time from Powerdown mode, see ADS122S14 data sheet Electrical Characteristics TableResponseN/A
DELAYProgrammable delay, use to account for external analog settling if necessaryUser ConfiguredDATA_RATE_CFG (0x06h)
CONVTotal conversion time, includes DELAYResponseN/A
DUTY CYCLEPercentage of [(START UP + CONV) / sensor cycle period]ResponseN/A

Figure 6-19 shows an example logic analyzer capture of the adc lowpwr 1000 command over a four-second period.

ADS122S14EVM adc lowpwr 1000 Logic Analyzer CaptureFigure 6-19 adc lowpwr 1000 Logic Analyzer Capture

Figure 6-20 shows an example terminal output when the ADC active period exceeds 90% of the user-input sensor cycle period. The terminal displays the minimum sensor cycle period based on the current ADC settings.

ADS122S14EVM adc lowpwr Sensor Cycle Period Too ShortFigure 6-20 adc lowpwr Sensor Cycle Period Too Short

Figure 6-21 shows an example of the proper syntax and response to stop the adc lowpwr stream mode: adc lowpwr stop.

Syntax: adc lowpwr stop

ADS122S14EVM adc lowpwr stop Terminal Input ExampleFigure 6-21 adc lowpwr stop Terminal Input Example

Figure 6-22 shows the total SNSR-DUAL-ADC-EVM supply current using the adc lowpwr 1000 command over a four-second period. The bridge switch is disabled, the ADS122S14 ADCs enter power-down mode, and the MSPM0 enters Sleep Mode during the low part of the duty cycle. This power cycling reduces the average current consumption over the 1000ms sampling period by 48%, from 4.5mA to 2.34mA. Save additional average power by reducing the conversion time, increasing the sensor cycle period, or putting the MCU into a lower power state.

ADS122S14EVM SNSR-DUAL-ADC-EVM Supply Current Over Time Using the adc lowpwr 1000 CommandFigure 6-22 SNSR-DUAL-ADC-EVM Supply Current Over Time Using the adc lowpwr 1000 Command

Figure 6-23 shows a breakdown of the supply current consumption of ADC1, ADC2, a 1.5kΩ (nominal) Wheatstone bridge, and the MSPM0 during normal operation of the SNSR-DUAL-ADC-EVM using the settings shown in Figure 6-18.

ADS122S14EVM Supply Current During Normal Operation by DeviceFigure 6-23 Supply Current During Normal Operation by Device