lpcware

LCP111x Board Not Working without Crystal

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by kralux on Tue Jul 06 11:49:28 MST 2010
We made our own LPC1111 target board without a crystal connected because we want to use the internal RC oscillator.
Unfortunately, when we connect it to the LPC Xpresso board LPC Link (or the red probe), it gets stuck somewhere in the bootloader code before reaching our entry point.

The specific line is line 421 of system_LPC11xx.c (by stopping execution with the debugger):
while (!(LPC_SYSCON->SYSPLLCLKUEN & 0x01));     /* Wait Until Updated       */

Apparently, it is waiting infinitely for the PLL.

According to our understanding, the LPC1111 should be able to run "out of the box" without a crystal attached.

In addition to this, we experimented on the LPCXpresso development board to rule out any issue with our board.
We simply unsoldered the crystal from that board and the same behavior was observed: the LPC would hang on the same line as shown in the debugger.
When we put the crystal back on the LPCXpresso board, it works as expected. When we take it out, the debugger hangs around the line mention above.

What should we do to run without a crystal? Do we need to modify the bootloader code? (though the documentation says it is made to run without a crystal).

Thank you for your help!

Outcomes