topic Re: oscillator is not known to declare in LPC Microcontrollers

oscillator is not known to declare

suraj78725 — Thu, 21 Jan 2021 04:14:07 GMT

hi i am suraj,

i have crossed across a doubt that what crystal is been associated to what register to declare either in function wise or register wise. is the order of the clock declaration really matters or just we can delcare and initiate the program with the clock.

i am using lpc54628 board and so the 12MHz and the EXT 25MHz frequency oscillator is the only only currently working for me and so can i use it for the other programs or couldn't i be?.

if can please tell me how

the flow of the order of declaring and the calling the clock is been referred by the following picture in the datasheet named LPC546XX and i've attach it here and the photo of the page for futher reference.

with regards

suraj

Re: oscillator is not known to declare

xiangjun_rong — Thu, 21 Jan 2021 06:30:01 GMT

Hi, Suraj,

As you know that the LPC54628 has independent XTALIN/XTALOUT pins, they can be connected to external crystal from 1MHz to 25MHz. After you clear bit 9 in Power Configuration register 0, and clear bit3 in Power Configuration register 1, the system oscillator will work, the clk_in clock signal will be available. You can set up the System oscillator control register to select clock frequency.

For example, You can use the CLOCK_AttachClk(kEXT_CLK_to_SYS_PLL); to route the CLK_In clock signal as PLL input signal.

Hope it can help you

XiangJun Rong

Re: oscillator is not known to declare

suraj78725 — Fri, 22 Jan 2021 06:36:01 GMT

hi xiang,

is the word pll in the sentence for the clock attachment means it is for only pll operation or for all sort of usage of the external clock in the program.

suraj

Re: oscillator is not known to declare

xiangjun_rong — Fri, 22 Jan 2021 07:07:04 GMT

Hi, Suraj,

Pls refer to the following Fig, the external crystal generates clock signal called clk_in, it can be one input source of Main clock select A, and one input source of PLL......, in other words, the external crystal clock is NOT only for PLL.

Hope it can help you

XiangJun Rong

Re: oscillator is not known to declare

suraj78725 — Sat, 23 Jan 2021 10:03:39 GMT

thanks for your response xiang