• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 79 subscribers
  • Views 1916 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LPM3 comparison between MSP432 and MSP4320F5328

Christopher Carl
Intellectual 350 points
Other Parts Discussed in Thread: MSP430F5328

Hello,

I am afraid I already know the answer to this, but I want to ask the experts just in case I am overlooking anything.  We are investigating the possibility of migrating form the MSP430F5328 to the MSP432 (evaluating with the MSP-EXP432P401R dev. board).  With the msp430, our application runs primarily in LPM3 mode with timers initiating wake ups.  In looking over the msp432 manual and data sheet, it appears that this approach will not work for LPM3, since all peripherals (including timers) are disabled with the exception of WDT and RTC; further, it looks like the DCO is turned off in this mode.  This leaves LPM0 as the only sleep mode we could enter in order to achieve the functionality we are looking for.

First off, I am hoping someone can tell me that I am interpreting this wrong and there is a way we can go into LPM3 while still using timers.  Next off, if we are limited to LPM0, it appears it is not going to come anywhere close to meeting our power budget that was set the msp430.  Is it possible to individually customize which modules are on and off while in LPM0 is order to save power and try to reach our power budget, or am I pretty much not going to come anywhere close to meeting the low power consumption of the msp430's LPM3 mode?

Thanks so much!

-Chris

  • 0
    TI__Guru**** 211917 points
    Christopher,

    You appear correct by stating that you will not be able to use timer interrupts in LPM3 and I do not think it is possible to individually set modules in LPM3 to save power. I have alerted a MSP432 expert to this thread so that he might shed some light on your choices regarding the situation at hand. Until he responds, would it be possible to use the RTC instead of a timer to produce your LPM interrupts? How what frequency do the interrupts need to occur?

    Regards,
    Ryan
  • 0 in reply to Ryan Brown1
    Intellectual 350 points
    Thanks for the response Ryan. I appreciate that you have passed this on to someone that could provide more details. I am currently implementing a solution using the RTC so I can do power comparisons. We will still need to enter LPM0 for ADC collection, but we are hopeful that the gains in LPM3 with the RTC will outdo the losses when we need to transition to LPM0. I will update when I have some further information.
  • 0 in reply to Christopher Carl
    TI__Genius 17802 points
    Hi Chris,
    Ryan is correct, for the MSP432P401R family, the only modules available in LPM3 are RTC, WDT, and GPIOs. The direction for the first device family of the MSP432P platform was to very aggressively power-gate and completely eliminate all leakage current from all other modules in LPM3 to drive the standby current down as much as possible (~850nA). This gives us a very competitive power number compared to MCUs in similar class of performance (M3/M4F, 90nm or smaller). Unfortunately the biggest drawback is the limitation both in terms of peripherals operating in LPM3 (RTC, WDT, GPIOs) as well as the wake-up interval granularity available to RTC & WDT. Hopefully the RTC pre-scalers PS0 & PS1 will give you enough granularity & flexibility to meet your customer's wake-up requirements.

    In the event that you absolutely need Timer_A for better wake-up resolution, we will need to look at LPM0. Do keep in mind though, that on MSP432 there is an additional LPM0 mode called Low-Frequency LPM0, where the device can operate at 32-128kHz and consume much less power than your regular LPM0 (~70uA). You can use this mode to operate your Timer_A and once the device wakes up, you can put the device into full-power mode to perform the ADC conversion. Here's an App. Note with more details on this Low-Frequency mode: www.ti.com/.../slaa657.

    Hopefully that'll give you some more info to figure out the ideal scenario for your customer. If you need to bounce around some more ideas, feel free to post more details in terms of requirements and what you have in mind in terms of power modes, RTC/Timer interval, wake-up latency before you need to start the ADC conversion, etc.. Our team will try to help you flesh out the solution and determine the lowest power profile possible that meets your customer's application requirements.

    ~Dung

**Attention** This is a public forum