topic LPC1114 without external crystal in LPCXpresso IDE

LPC1114 without external crystal

lpcware — Thu, 16 Jun 2016 02:05:22 GMT

Content originally posted in LPCWare by chucks13 on Mon Mar 07 11:46:33 MST 2011
Hello, I am new to the forums, so if the is an FAQ, please forgive me

I have a target board based on the LPCXpresso 1114 board. My target board has no crystal, because I was assured that it run without it using the PLL to drive the system clock, up to at least 48 Mhz, and hopefully 50. The standard examples which I believe are suppose to activate the PLL have on this line:
while (!(LPC_SYSCON->SYSPLLSTAT & 0x01)); /* Wait Until PLL Locked */

This is in the library SystemInit() function. My board makes it to this line and hangs. The obvious reason is that the PLL never acquires a lock. I have not made any changes to the initialization code.

I fear that I have missed something, like an external resistor that the LPCXpresso board with the crystal doesn't need, or the standard examples needs something more.

Thanks for reading my post.

Chuck

Re: LPC1114 without external crystal

lpcware — Thu, 16 Jun 2016 02:05:22 GMT

Content originally posted in LPCWare by Luis Digital on Mon Mar 07 11:59:03 MST 2011
Hi,

View: [B]LPC11xx basics required[/B]

Re: LPC1114 without external crystal

lpcware — Thu, 16 Jun 2016 02:05:23 GMT

Content originally posted in LPCWare by Ex-Zero on Mon Mar 07 14:27:24 MST 2011
A few lines above you find:

LPC_SYSCON->SYSPLLCLKSEL = SYSPLLCLKSEL_Val; /* Select PLL Input

This value sets the PLL circuit input source (see table 15 UM10398).

If it's 1 you try to use 'system oscillator' = crystal. Could be a problem :)

If you change it to 0, you can use IRC = internal RC oscillator (12MHz)

Note: IRC accuracy is just 1%

Re: LPC1114 without external crystal

lpcware — Thu, 16 Jun 2016 02:05:24 GMT

Content originally posted in LPCWare by chucks13 on Mon Mar 07 16:26:05 MST 2011
//#define SYSPLLCLKSEL_Val 0x00000001 // This sets to use external crystal for clock source for PLL
#define SYSPLLCLKSEL_Val 0x00000000 // Set PLL input to internal RC oscillator

Thank you. This fixed my problem.