SDAA388 August   2026 MSPM33C321A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Firmware Updates on MSPM0 and MSPM33 MCU
    2. 1.2 Power Modes on the MSPM0 and MSPM33
  5. 2How the IO Latches Work
    1. 2.1 How the IO State Gets Latched
    2. 2.2 Maintaining IO State During the Bootprocess
  6. 3Configuring Software Around Shutdown IO Functionality
    1. 3.1 Configuring software to wake from shutdown
    2. 3.2 Using State Retention IOs With Bootloaders
    3. 3.3 Shutdown Memory
  7. 4Summary
  8. 5References

Abstract

MCUs typically drive multiple signals to other ICs on a PCB using GPIOs. The voltage level of these GPIOs can be critical to maintain for the lifecycle of the MCU. Most MCU's require a reset to perform a firmware update. This causes a problem for applications that both require a firmware update and need to maintain a certain GPIO voltage. To maintain the GPIO voltage through a firmware update the MSPM0 and MSPM33 devices provide a methodology to latch the IO state before performing the reset required for a bootprocess. To set these latches the device must enter a low power mode called shutdown but this causes an additional problem of waking up the device. This document goes over how to trigger these latches, how to automatically wake up the MCU after shutdown, how to build a software application to achieve this functionality, and use cases for the boot process.