CCS/MSP430FR2433: ACLK Source Select VLO

Per FR2 User Guide (SLAU445H) Section 3.1 and Table 3-8, ACLK can only use VLOCLK in the "Enhanced" clock system. As far as I know, the only FR2 with an Enhanced CS is the FR2355. You can connect VLOCLK directly to the RTC and the WDT.

I was also a bit surprised when I discovered this, since earlier devices had that option.

Hi Jame,

The ACLK can't be sourced from VLOCK. But the MCLK can be sourced from VLO.

B.R
Winter

Ah ok, so if I wanted to use a timer based  interrupt (say; wake up once a day), I set the RTC to use VLO?

I am basing this of the example 'msp430fr243x_LPM3_02.c' in TIREX. I was hoping to get <2ua with this example but I assume because of:

CSCTL4 = SELMS__DCOCLKDIV | SELA__REFOCLK;  // set default REFO(~32768Hz) as ACLK source, ACLK = 32768Hz

                                                                                            // default DCOCLKDIV as MCLK and SMCLK source

 I get that extra power usage? 

Thanks for the info. It would be nice if there were some examples provided on TIREX for using VLO :)

Hi,

There is not example for using VLO right now. Thanks for your suggestion. We will consider your requirement.

B.R
Winter

Hey Winter, I'm abit confused about this. Can you explain it in more detail? Thanks

Hi Jame,

The RTC can source from VLOCLK and wake up device from LPM3.5 to get a lower power consumption up to 0.75uA.

 

B.R

Winter