LPC845 FRO control register

[lajostoth]

Hi,

This is a snippet of 845 SDK :

I can't find any information about [1:0] bits of FROOSCCTRL register in the user manual.

These data are confidential ?

[Alexis_A]

Hi Lajos Toth,

These bits are set in the set_fro_frequency() API, this function is located in the boot ROM. In the SDK you can found it with the following name and the argument helps you to modify the output frecuency:

 CLOCK_SetFroOscFreq(kCLOCK_FroOscOut18M);   /*!< Set up FRO freq to 18MHz */

 CLOCK_SetFroOscFreq(kCLOCK_FroOscOut24M);   /*!< Set up FRO freq  to 24MHz*/

 CLOCK_SetFroOscFreq(kCLOCK_FroOscOut30M);   /*!< Set up FRO freq  to 30MHz*/

Hope it helps you,

Alexis Andalon

[lajostoth]

Thank you Alexis Andalon for your answer. The reason of my question was that I have trouble with get clock functions.

I created a simple USART project transmit data to VCOM port:

This is clocks diagram of USART0:

If I change CLOCK_GetFRG0ClkFreq() to 30000000U the usart works well, but the function returns  wrong value(13222784)

[Alexis_A]

Hi Lajos Toth,

I think you're confusing the FRG Clock with the FRO clock, these are two diferent clock options.

In the USART_Init, you're using CLOCK_GetFRG0ClkFreq() but the original question is about the CLOCK_GetFroFreq()

Best Regard,

Alexis Andalon

[lajostoth]

Hi Alexis Andalon,

I am not confusing with clocks,  CLOCK_GetFRG0ClkFreq() call CLOCK_GetFroFreq() function if the clock source for FRG is setting to FRO. The problem is solved, there is a type casting bug in CLOCK_GetFRG0ClkFreq() function as well as in FRG1.

Best Regards