程序执行期间更改CPU时钟速度

Question

Main applicataion on our micro (RH850) were developed to work with clock speed X Mhz. Bootloader which is alwyas executed first, initializes clock speed to X/3 MHz. We cant change speed in bootloader to X Mhz, due to some limiations within libaraires which are used by the bootloader.

Is there any possiblity to reinitialize clock speed in bootloader from X/3 Mhz to X MHz, lets say, just before bootloader does jump to application?

What is the common practice of such a clock handling embedded systems? Is there any general way, or is this rather micro specific?

regards J.

Answer 1

So it worked in following way:

1. switch back to main oscillator
2. disable PLLs
3. reconfigure PLLs
4. enable PLLs
5. change CPU source to PLL you just reconfigured