MSP430FR2153: Using higher frequency than 32.768 kHz in LF mode (FR2xxx)

O.H

Part Number: MSP430FR2153

Hi experts,

Is it possible to connect a 38.4kHz crystal to XT1 with MSP430FR2153 (FR2xx series Clock System)?

My customer wants to do UART communication, but the device to connect to is fixed at 4800 bps. We believe that if we input a 38.4kHz crystal to ACLK=BCLK, we can theoretically communicate with an error rate of TX=±0%, RX=±6.25%. (This is when the accuracy of the crystal is ignored.)

I understand from the user's guide "NOTE: XT1 in HF mode configuration" that the input cannot exceed 40 kHz.

Best regards,
O.H

over 3 years ago

+1 Eason Zhou over 3 years ago

TI__Mastermind 39775 points

Hi,

Yes, customer can do that. This only can make sure the low error for TX, but there will be high error on TX.

I think the problem is that whether customer will use external crystal for SMCLK. I would suggest to use internal oscillator, as PLL may not lock if you use a frequency besides of 32.768, because we only will trim the 16MHz PLL when sourced from 32.768kHz.

0 O.H over 3 years ago in reply to Eason Zhou

Mastermind 6430 points

Hi,

Sorry for the delay in replying. I understood. Thank you for your support!

Best regards,
O.H

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MSP430FR2153: Using higher frequency than 32.768 kHz in LF mode (FR2xxx)