Jens Prüfer wrote:
Hello,
I got TI's msp430f149 development board that comes with the JTAG interface, a
ZIF socket for the QFP64 chips and a lose 32.768 kHz crystal. Has anyone ever
gotten the system up to 8 MHz using that kit? All examples I can find are
utilizing a seperate 8 MHz crystal on the XT2 input.
However, the documentation states, it is possible to use the LF crystal
instead and set up some registers with correct multipliers etc. to generate
the 8 MHz MCLK. Unfortunately the documentation is incomprehensible to me and
there is no sample code whatsoever how to set everything up.
Has anyone here ever used the FLL got it up and running? I'd appreciate some
documented code snippet how and which registers to set up. I already see the
difficulty getting the right load capacitors set up because the shipped
crystal requires 12.5 pF.
I wish TI had better documentation on that clock FLL with all registered and
possible settings listed in a well documented table.
Cheers
Jens
One of the biggest drawbacks of the MSP430 is the write only
documentation. :-)
The 149 doesn't use the FLL. It has the basic clock. You can get an FLL
part up to 8MHz real easy, by setting the appropriate ratios in the FLL
registers. The devices with the basic clock need a little more work.
P2.5 can be set to be a frequency control pin, using the P2SEL register.
The internal switchable resistors only get you up to about 5MHz. A
resistor from P2.5 to Vcc will take you as high as you like, until the
device trips over - could be 20MHz on some devices :-)
Regards,
Steve
