SLAA828B March   2018  – August 2021 MSP430FR2000 , MSP430FR2032 , MSP430FR2033 , MSP430FR2100 , MSP430FR2110 , MSP430FR2111 , MSP430FR2310 , MSP430FR2311 , MSP430FR2422 , MSP430FR2433 , MSP430FR2512 , MSP430FR2522 , MSP430FR2532 , MSP430FR2533 , MSP430FR2632 , MSP430FR2633 , MSP430FR4131 , MSP430FR4132 , MSP430FR4133

 

  1.   Trademarks
  2. 1Introduction
  3. 2ADC Low-Power Sampling Software Design
    1. 2.1 System Clock Source Selection
    2. 2.2 ADC Clock Source Selection
    3. 2.3 Initialization of Unused GPIO Pins
  4. 3ADC Error Correction and Experimental Testing
    1. 3.1 Error Correction
    2. 3.2 Accuracy Test
  5. 4Time-Division Multiplexing of the ADC to Achieve Additional Channel Acquisition
  6. 5Summary
  7. 6References
  8. 7Revision History

2 ADC Low-Power Sampling Software Design

This document lists the main factors that affect power consumption with the on-chip ADC sample solution in MSP430FR4xx/FR2xx devices with 10-bit ADC. The power consumption results are given with different configurations. This example uses the 1.5-V internal reference voltage. Because the ADC trigger signal does not stop or start the 1.5-V internal reference voltage automatically, software can enable the 1.5-V REF and wait approximately 30 µs before triggering the ADC in the RTC interrupt. Software can also stop the reference in the ADC conversion ready interrupt. The following test is based on this approach. Developers can optionally keep the internal reference enabled all the time at the expense of higher power consumption.

Some MSP430FR4xx and MSP430FR2xx devices have a 12-bit ADC with an internal reference voltage that can be turned on and off automatically during an ADC conversion. Besides this exception, the implementation of battery voltage measurement with these devices is similar to the devices with 10-bit ADC; however, implementation details are outside the scope of this document.