Hello, I have an Logomatic-v23 board from Sparkfun electronics. I want to use an ADXL213AE accelerometer. The ADXL send his PWM output value and i want to capture it using the CAP0.0 input of the LPC2148. Unfortunately I have tried the following code and it don't want to acquire the value. Initialization :
//Enable Interrupts VPBDIV=1; // Set PCLK equal to the System Clock VICIntSelect = ~(UART1_INT | RTC_INT | TIMER0_INT); VICVectCntl0 = 0x20 | 7; //Set up the UART1 interrupt VICVectAddr0 = (unsigned int)ISR_RxData1; VICVectCntl1 = 0x20 | 13; //Set up the RTC interrupt VICVectAddr1 = (unsigned int)ISR_RTC; VICVectCntl2 = 0x20 | 4; //Timer 0 Interrupt VICVectAddr2 = (unsigned int)ISR_Timer0; //TIMER0 setup T0TCR = 0x02; // TIMER0 Disable; reset T0TC & T0PC T0PR = 0x00000000; // Reset T0PR T0CTCR = 0x00; // Timer Mode: every rising PCLK edge T0CCR = 0x06; // Capture on CAPn.0 falling edge and Interrupt on CAPn.0 event |
static void ISR_Timer0(void) { //Interrupt Code Here T0TCR = 0x02; // TIMER0 Disable; reset T0TC & T0PC T0PR = 0x00000000; // Reset T0PR YPacc = T0CR0; //Get accelerometer captured value T0IR = 0xFF; //Clear the timer interrupt T0TCR = 0x01; // TIMER0 Enable VICVectAddr =0; //Update the VIC priorities } |
Main code :
rprintf_devopen(putc_serial0); //Init rprintf rprintf("ADXL2148 Accelerometer Yp raw data :\n\r"); VICIntEnable |= TIMER0_INT; //Enable Timer0 Interrupts T0TCR = 0x01; // TIMER0 Enable while( 1 ) { rprintf("T0CR0:%i\n\r",T0TC); } |
Output on Hyperterminal :
ADXL2148 Accelerometer Yp raw data : T0CR0:369396 T0CR0:139755 T0CR0:271646 T0CR0:539757 T0CR0:311754 |
And the value is never the same... Does anybody could help me to find my problem?
I have made a mistake in my previous post : Main code should be :
rprintf_devopen(putc_serial0); //Init rprintf rprintf("ADXL2148 Accelerometer Yp raw data :\n\r"); VICIntEnable |= TIMER0_INT; //Enable Timer0 Interrupts T0TCR = 0x01; // TIMER0 Enable while( 1 ) { rprintf("T0CR0:%i\n\r",YPacc); } |
And the result output is now :
ADXL2148 Accelerometer Yp raw data : T0CR0:4326756 T0CR0:4325926 T0CR0:4324216 T0CR0:4324036 T0CR0:4326626 T0CR0:4324236 |
It seems working now. Thanks
Ok, now it detect falling edge of pwm signal but it always capture the total period and not the duty cycle of my signal. I need to capture the duty cycle to have a correct value of my ADXL.
I have solved my problem. Here is my personal solution to get the duty cycle of the original pwm incoming signal: Main code :
rprintf_devopen(putc_serial0); //Init rprintf rprintf("ADXL2148 Accelerometer Yp raw data :\n\r"); while( 1 ) { VICIntEnable |= TIMER0_INT; // Enable Timer0 Interrupts T0TCR = 0x01; // TIMER0 Enable delay_ms(20); // Do some acquisition T0TCR = 0x00; // TIMER0 Disable VICIntEnClr |= TIMER0_INT; // Stop Timer0 Interrupts result = T1/((T1+T2)/100); // Duty cycle calculation in percent if( (result > (oldresult+1)) || (result < (oldresult-1)) ) // If detect movement { i=100; rprintf("%d ", result ); } } |
Interrupt section :
static void ISR_Timer0(void) { //Interrupt Code Here T0TCR = 0x02; // TIMER0 Disable; reset T0TC & T0PC T0PR = 0x00000000; // Reset T0PR if(state) { T1 = T0CR0; T0CCR = 0x06; // Capture on CAPn.0 falling edge and Interrupt on CAPn.0 event state = 0; } else { T2 = T0CR0; T0CCR = 0x05; // Capture on CAPn.0 rising edge and Interrupt on CAPn.0 event state = 1; } T0IR = 0xFF; //Clear the timer interrupt T0TCR = 0x01; // TIMER0 Enable VICVectAddr =0; //Update the VIC priorities } |
It should be working, but adjust the "delay_ms(20);" in the main code section according to the period of your pwm signal.
hello sir, i am also try to access capture mode in timer0,but can't get the output..i am try to calculate frequency using this mode.. plz send ur code so i can get some idea.. thank you....
I can print anything with
rprintf("T0CR0:%i\n\r",T0TC); !!!
rprintf is not possible for uVision 4 ?
Can you tell me how I can use this software for rotary encoder
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