LPC1758 how to get 32KHz from RTC

Development Boards MicroMod
1

Hello,

I am porting my code from LPC2148 to LPC1758. There is a change in RTC registers, so now it is not possible to read directly 32768 tick counter in LPC17xx.

My options I think are:

  1. Use RTC output and Timer0 capture input.

  2. Program timer0 to count 32768 ticks per seconds and then calibrate it every second via RTC 1 second interrupt.

  3. I have read that Watchdog timer can be driven via RTC 32KHz output, but I am not sure that I can rely on it’s timer counter after that.

Do I have any other options?

2

You could run the main clocks using the PLL to multiply up the 32 KHz.