int Timer_FreeCountingMode(void)
{
int volatile i;
/* Init System, IP clock and multi-function I/O
In the end of SYS_Init() will issue SYS_LockReg()
to lock protected register. If user want to write
protected register, please issue SYS_UnlockReg()
to unlock protected register if necessary */
SysInit();
/* Init UART to 115200-8n1 for print message */
UART_Open(UART0, 115200);
printf("\nThis sample code demonstrate timer free counting mode.\n");
printf("Please connect input source with Timer 0 capture pin PD.11, press any key to continue\n");
UART_GeyChar();
// Give a dummy target frequency here. Will over write capture resolution with macro
TIMER_Open(TIMER0, TIMER_PERIODIC_MODE, 1000000);
// Update prescale to set proper resolution.
// Timer 0 clock source is 12MHz, to set resolution to 1us, we need to
// set clock divider to 12. e.g. set prescale to 12 - 1 = 11
TIMER_SET_PRESCALE_VALUE(TIMER0, 11);
// Set compare value as large as possible, so don't need to worry about counter overrun too frequently.
TIMER_SET_CMP_VALUE(TIMER0, 0xFFFFFF);
// Configure Timer 0 free counting mode, capture TDR value on rising edge
TIMER_EnableCapture(TIMER0, TIMER_CAPTURE_FREE_COUNTING_MODE, TIMER_CAPTURE_RISING_EDGE);
// Start Timer 0
TIMER_Start(TIMER0);
// Enable timer interrupt
TIMER_EnableCaptureInt(TIMER0);
NVIC_EnableIRQ(TMR0_IRQn);
while(1);
}
/*---------------------------------------------------------------------------------------------------------*/
int main(void)
{
volatile uint32_t u32InitCount;
uint32_t au32CAPValus[10];
/* Unlock protected registers */
SYS_UnlockReg();
/* Init System, peripheral clock and multi-function I/O */
SYS_Init();
/* Lock protected registers */
SYS_LockReg();
/* Init UART0 for printf */
UART0_Init();
printf("\n\nCPU @ %d Hz\n", SystemCoreClock);
printf("+---------------------------------------------------+\n");
printf("| Timer External Capture Function Sample Code |\n");
printf("+---------------------------------------------------+\n\n");
printf("# Timer Settings:\n");
printf(" Timer0: Clock source is 12 MHz; Toggle-output mode and frequency is 500 Hz.\n");
printf(" Timer3: Clock source is 12 MHz; Toggle-output mode and frequency is 1 Hz.\n");
printf(" Timer2: Clock source is HCLK(72 MHz); Continuous counting mode; TCMP is 0xFFFFFF;\n");
printf(" Counter pin enable; Capture pin and capture interrupt enable;\n");
printf("# Generate 500 Hz frequency from TM0 and connect TM0 pin to Timer2 counter pin.\n");
printf("# Generate 1 Hz frequency from TM3 and connect TM3 pin to TM2_EXT capture pin.\n");
printf("# Get 500 event counts from Timer2 counter pin when each TM2_EXT pin interrupt occurred.\n\n");
/* Initial Timer0 and Timer3 default setting */
TIMER_Open(TIMER0, TIMER_TOGGLE_MODE, 1000);
TIMER_Open(TIMER3, TIMER_TOGGLE_MODE, 2);
/* Initial Timer2 default setting */
TIMER_Open(TIMER2, TIMER_CONTINUOUS_MODE, 1);
/* Configure Timer2 setting for external counter input and capture function */
TIMER_SET_PRESCALE_VALUE(TIMER2, 0);
TIMER_SET_CMP_VALUE(TIMER2, 0xFFFFFF);
TIMER_EnableEventCounter(TIMER2, TIMER_COUNTER_FALLING_EDGE);
TIMER_EnableCapture(TIMER2, TIMER_CAPTURE_FREE_COUNTING_MODE, TIMER_CAPTURE_FALLING_EDGE);
TIMER_EnableCaptureInt(TIMER2);
/* Enable Timer2 NVIC */
NVIC_EnableIRQ(TMR2_IRQn);
/* Clear Timer2 interrupt counts to 0 */
u32InitCount = g_au32TMRINTCount[2] = 0;
/* Start Timer0, Timer2 and Timer3 counting */
TIMER_Start(TIMER0);
TIMER_Start(TIMER2);
TIMER_Start(TIMER3);
/* Check TM2_EXT interrupt counts */
while(1) {
if(g_au32TMRINTCount[2] != u32InitCount) {
au32CAPValus[u32InitCount] = TIMER_GetCaptureData(TIMER2);
printf("[%2d] - %4d\n", g_au32TMRINTCount[2], au32CAPValus[u32InitCount]);
if(u32InitCount > 1) {
if((au32CAPValus[u32InitCount] - au32CAPValus[u32InitCount - 1]) != 500) {
printf("*** FAIL ***\n");
while(1);
}
}
u32InitCount = g_au32TMRINTCount[2];
}
if(u32InitCount == 10)
break;
}
/* Stop Timer0, Timer2 and Timer3 counting */
TIMER_Close(TIMER0);
TIMER_Close(TIMER2);
TIMER_Close(TIMER3);
printf("*** PASS ***\n");
while(1);
}
