MSP430F5438A clock settings

Jacktang

MSP430F5438A clock settings [Copy link]

Using MSP430F5438A, XT2 with an external 25MHz crystal oscillator, I wrote a clock driver, but it does not work properly. I am pasting this code here.

This code sets MCLK, SMCLK and ACLK to XT2, which has achieved the best performance. The key codes have been explained. However, this program does not work properly. After carefully checking the TI official manual, the problem is that the VCore inside the CPU is not set correctly.
The 5xx and 6xx series of MSP430 have an integrated linear regulator inside the chip, which can reduce the external voltage to a lower voltage to save power, but the reduction of VCore will slow down the CPU speed, so in order to achieve the CPU running speed, it is necessary to match the VCore voltage. The matching table is shown in the figure below.

According to this table, if you want the CPU to run at 25MHz, you need to set the PMMCOREV flag to 3. The modified code is shown in the figure below.

This program runs normally and stably.