AnsweredAssumed Answered

ATIMER w/o 32kHz crystal

Question asked by Yuri Ivanov on Sep 26, 2016
Latest reply on Oct 7, 2016 by Yuri Ivanov

Good day.

I have two identical custom board with LPC4357FET256.

One with 32kHz oscillator crystal connected to chip. And another w/o crystal.

But... On both board ATIMER worked. How it's possible ?

Initialize like this:

LPC_CREG->CREG0 &= ~((1 << 3) | (1 << 2));
LPC_CREG->CREG0 |= (1 << 1) | (1 << 0);

LPC_ATIMER->DOWNCOUNTER = 2048;
LPC_ATIMER->PRESET = 2048;

 

and put DOWNCOUNTER to LCD:

lpc_printf(10,20,"%d",LPC_ATIMER->DOWNCOUNTER);

 

On both board value changed identical.

 

UM10503 v2.1 Chapter 36:

"Alarm timer counter register (DOWNCOUNTER, see Table 866), which counts down from a preset value using the
1024 Hz signal derived from the 32 kHz oscillator."

 

32kHz oscillator crystal NOT present on the second board, but ATIMER is worked...

Outcomes