MSP430I2021: Accuracy of ACLK

Linus Kerk1

Prodigy 200 points

Part Number: MSP430I2021

I would like to use the ACLK as a source clock to TimerA to generate an interrupt every second.

I would use this interrupt to help keep track of time up to 24 hrs.

What is the accuracy of the ACLK and how it varies from chip to chip?

I considered using SMCLK but with the SMCLK freq, it would generate the interrupt too frequently.

over 3 years ago

0 James Evans over 3 years ago

TI__Mastermind 49692 points

Hello,

ACLK is sourced by the 16.384 MHz DCO and just divided by 512 to achieve 32 kHz. Timer_A is a 16-bit timer, so counting to 32,000 (111 1101 0000 0000) is possible. Thus, the accuracy will depend on the accuracy of the DCO. For that, you can find the frequency and performance data in the datasheet. To improve accuracy, you may want to use a high-precision, high-tolerance external 20 kOhm resistor for ROSC.

Regards,

James

0 Linus Kerk1 over 3 years ago in reply to James Evans

Prodigy 200 points

Hi James,

thanks. So in terms of accuracy, there is no difference if I choose ACLK or SMCLK since they both came from the same source.

Thanks again.

Linus

0 James Evans over 3 years ago in reply to Linus Kerk1

TI__Mastermind 49692 points

That's correct.

Regards,

James

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MSP430I2021: Accuracy of ACLK