Do I need external crystal for MSP430F5500 to use USB?

Hi,

no, you can't use the internal OSC for USB! You need (at least) a 4MHz crystal to feed the USB PLL! Refer to the users manual for details!

Rgds
aBUGSworstnightmare 

On TI's development kits they use a 4 MHz Burklin crystal 78D134. (You can verify this on the BOM for them, like the MSP-TS430PN80USB)

https://www.buerklin.com/default.asp?l=e

Just search for 78D134. I have ordered a few for a project I'm working on.

On the F552X series you can also use 8 or 12 MHz. You can use other types of cystals but it might require a custom BSL.

The 5500 might work a little differently, so make sure you read the data sheets on it.

Bill

Dear Bill 

If I want to change the 4MHz crystal to 20MHz Crystal , is the C1 C2 still 12pF?

Thanks & Regards

SC Huang

I'm pretty sure you need to change them. (maybe a higher value but I don't remember) The data sheets have some info. The MSP430 also has internal adjustment as well.

http://focus.ti.com/lit/ds/symlink/msp430f5529.pdf page 56

http://focus.ti.com/lit/ug/slau208h/slau208h.pdf page 90

http://www.ti.com/litv/zip/slac300c This contains example code, some of which pertains to setting the clock frequency.

http://focus.ti.com/lit/an/slaa395/slaa395.pdf new quickstart guide

On my boards I have purchased/built with the F552x series, I did some experimentation with the clocks.

To run the CPU at high frequencies, you have to raise the voltage in increments, TI has example code for this. (just copy and paste the reference function, and run it 3 times in a row, then set the cpu to high frequency) I was able to run from the DCO at 25MHz flawlessly using the reference code.

I haven't had much time to mess with the crystals on the board we made for our project, and I think I might have messed the design up anyway. (even though I used the same crystal TI did in the reference board) This might be a software issue though. But I won't have time to investigate till later this summer.

You should start a new thread about 20MHz crystals on the specific MSP430 you want to use and wait for someone from TI to help. Unless they answer here. I'm not a crystal expert.