MSP430F6636: which frequency should be supported to MSP430F6636

This part can work with MCLK up to 20MHz per datasheet. Similar part is overclocked in MSP-FET to 22 MHz.

If you don't use USB, or don't need factory HID BSL, than you can use any XT2 up to 20MHz, if you want to source MCLK directly (precise clock) from XT2.

If you want to use factory HID BSL, than XT2 must be 4, 8, 12 or XX MHz (XX is 24MHz in msp430 devices with max MCLK of 24 MHz, not sure about value for devices with limited MCLK to 20Mhz).

If you want to use USB, than calculator can be used to see matched XT2 value...

5531.MSP430USBCalc.zip

Thanks for the information.
Furthermore, We are not using USB / HID BSL in our application.
Also in our hardware, we have connected 24 Mhz crystal in XT2, So can we use same and configure 20 Mhz from firmware, or do we need to connect 20Mhz crystal explicitly.

Thanks,

Vivek

Thanks for the information.

We need some details about the Crystal drift.

1. If we will go with Internal Reference crystal 32.768KHz with Auto calibrate please find the below Image where we calling the API. But there is some drift is present according the Data Sheet. Can you please suggest that How to reduce the drift?

2. Could we calibrate the DCO output(Ex 20Mhz) frequncy using external crystal(20Mhz) frequncy as a reference.
-  MSP430F6636 is supporting  upto 20Mhz frequncy.
- Now we want to calibrate this 20Mhz which is generated by DCO and internally they are stabilise this frequency using FLL.
- After that DCOCLK output drift is there. Could I reduce this drift using external crystal as a reference frequency(20MHz).

3. And  we are also using external 20MHz. Please find the below Image where we configuration with help of the API. So here,How much drift is possible and Is it reliable to go with external  20MHz ?

Hi Vivek,

For DCO accuracy, this is depend on reference clock as the below:

You can use internal 32768Hz REFO as the reference(like green), you also can use XT2 external crystal as the reference(like red).

There are will have some prescale... div...parameter to handle these reference clocks.

Thus if you would like a high accuracy DCO clock, you have to use a high accurcay reference clock.

For internal REFO:

For XT2(external crystal), the accuracy depend on crystal's spec.

Thanks!

Best Regards

Johnson