Required information regarding frequency generation in LPC11xx

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Hi All!!

 

As i'm very new to embedded domain of ARM lpc11xx, i'm going through

all the basics and the examples of the controller.
 

I need to generate 9hz for particular time duration[say for 20 secs/min],

and another freq of 12hz for 25secs/min.
 

Below is the part of the code where i'm getting the variable frequency of

9.4hz,7.6hz,12hz, whereas I have only assigned [1/1000us = 1khz],

void timer16_0_init(uint32_t delayInMs) //for frequency part
{
volatile unsigned int i;                 
 LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 7);        //enables clock for 16-bit counter/timer 0
 LPC_SYSCON->SYSAHBCLKCTRL |= (1 << ;        //enables clock for 16-bit counter/timer 1
//PIO0_8
 LPC_IOCON->PIO0_8 &= ~((1<<10)|(1<<5)|(3<<3)|(7<<0));
 LPC_IOCON->PIO0_8 |=  ((2<<3)|(2<<0));               

 LPC_TMR32B0->MR0 = 50 * ((SystemCoreClock/(LPC_TMR32B0->PR+1))/100);
  LPC_TMR16B0->PR  = 00;               
  LPC_TMR16B0->MR3 = 1000;//freq is generated at this point of match register          
  LPC_TMR16B0->MR0 = LPC_TMR16B0->MR3/4;    //MAT0 1/4 low, 3/4 high
  LPC_TMR16B0->PWMC = ((1<<0)|(1<<1)); 
  LPC_TMR16B0->TCR = 1;                    //start timer 0//clock runs & tim dec
  
}
 

Kindly give me some hint on how to set the time duration for particular frequencies.

Thank you.

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