What is RTCPS? ... MSP430F5529

460822

I see RTCPS displayed under Registers (Code Composer 4) -> RTC__Real_Time_Clock -> RTCPS. I don't see a detailed description in the Msp430x5xx & 6xx User Guide Manual ... slau208h. Is this msec in an unsigned int format?

over 12 years ago

0 old_cow_yellow over 12 years ago

Guru 58965 points

It is the symbolic name of a pre-scaler in the RTC module. Usually the address is at 0x04AC.

0 460822 over 12 years ago in reply to old_cow_yellow

Genius 4055 points

I don't see a detailed description in the Msp430x5xx & 6xx User Guide Manual ... slau208h.

0 Jason Kriek over 12 years ago

TI__Expert 5200 points

It is located on page 589 ->590 of the latest user guide. It is a prescaler of the input clock. So the time based will be based on your input clock divided by the prescaler that you would choose.

http://www.ti.com/lit/ug/slau208k/slau208k.pdf

-Jason

0 460822 over 12 years ago in reply to Jason Kriek

Genius 4055 points

I don't see RTCPS on pages 589-590.

0 Leo Hendrawan over 12 years ago in reply to 460822

TI__Guru 56650 points

Hi,

RTCPS = RT0PS + RT1PS.

See the register description below:

as you can see above RTCPS is basically the name of 16 bit register at offset 0x0C, containing basically 2 8-bit registers RT0PS and RT1PS.

0 460822 over 12 years ago in reply to Leo Hendrawan

Genius 4055 points

If I interpret this correctly, in the calendar mode, RT0PS can be interpreted in msec => RT0PS / 128 * 1000.

0 Leo Hendrawan over 12 years ago in reply to 460822

TI__Guru 56650 points

Hi,

i am not really sure what you are trying to do here. Are you trying to read the RT0PS directly? If yes, what would you do that?

In my opinion, since the RT0PS is sourced directly from 32768 Hz input in calendar mode, the content of RT0PS in milliseconds should be: N * 1000 / 32768 ms.

Anyway, from the current SLAU208K User's Guide chapter 22.2.2.1 you can find the information:

The prescale dividers, RT0PS and RT1PS, are automatically configured to provide a 1-s clock interval for the RTC_A. RT0PS is sourced from ACLK. ACLK must be set to 32768 Hz (nominal) for proper RTC_A calendar operation. RT1PS is cascaded with the output ACLK/256 of RT0PS. The RTC_A is sourced with the /128 output of RT1PS, thereby providing the required 1-s interval.

Hope this helps.

0 460822 over 12 years ago in reply to Leo Hendrawan

Genius 4055 points

I understand. The block diagram on page 566 was misinterpreted ... the output of RT0PS is not 100, but the overflow after 111.

A break point in the ISR that breaks every second (calendar mode) shows RTCPS toggling between 0x0080 and 0x8080 => 0.0039 secs and 1.0039 secs.

**Attention** This is a public forum

MSP low-power microcontrollers

MSP low-power microcontroller forum

What is RTCPS? ... MSP430F5529