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 :
1 | //Enable Interrupts
|
2 | VPBDIV=1; // Set PCLK equal to the System Clock |
3 | VICIntSelect = ~(UART1_INT | RTC_INT | TIMER0_INT); |
4 | VICVectCntl0 = 0x20 | 7; //Set up the UART1 interrupt |
5 | VICVectAddr0 = (unsigned int)ISR_RxData1; |
6 | VICVectCntl1 = 0x20 | 13; //Set up the RTC interrupt |
7 | VICVectAddr1 = (unsigned int)ISR_RTC; |
8 | VICVectCntl2 = 0x20 | 4; //Timer 0 Interrupt |
9 | VICVectAddr2 = (unsigned int)ISR_Timer0; |
10 | |
11 | //TIMER0 setup
|
12 | T0TCR = 0x02; // TIMER0 Disable; reset T0TC & T0PC |
13 | T0PR = 0x00000000; // Reset T0PR |
14 | T0CTCR = 0x00; // Timer Mode: every rising PCLK edge |
15 | T0CCR = 0x06; // Capture on CAPn.0 falling edge and Interrupt on CAPn.0 event |
1 | static void ISR_Timer0(void) |
2 | {
|
3 | //Interrupt Code Here
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4 | T0TCR = 0x02; // TIMER0 Disable; reset T0TC & T0PC |
5 | T0PR = 0x00000000; // Reset T0PR |
6 | |
7 | YPacc = T0CR0; //Get accelerometer captured value |
8 | |
9 | T0IR = 0xFF; //Clear the timer interrupt |
10 | T0TCR = 0x01; // TIMER0 Enable |
11 | VICVectAddr =0; //Update the VIC priorities |
12 | }
|
Main code :
1 | rprintf_devopen(putc_serial0); //Init rprintf |
2 | rprintf("ADXL2148 Accelerometer Yp raw data :\n\r"); |
3 | |
4 | VICIntEnable |= TIMER0_INT; //Enable Timer0 Interrupts |
5 | T0TCR = 0x01; // TIMER0 Enable |
6 | |
7 | while( 1 ) |
8 | {
|
9 | rprintf("T0CR0:%i\n\r",T0TC); |
10 | }
|
Output on Hyperterminal :
1 | ADXL2148 Accelerometer Yp raw data : |
2 | T0CR0:369396 |
3 | T0CR0:139755 |
4 | T0CR0:271646 |
5 | T0CR0:539757 |
6 | 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 :
1 | rprintf_devopen(putc_serial0); //Init rprintf |
2 | rprintf("ADXL2148 Accelerometer Yp raw data :\n\r"); |
3 | |
4 | VICIntEnable |= TIMER0_INT; //Enable Timer0 Interrupts |
5 | T0TCR = 0x01; // TIMER0 Enable |
6 | |
7 | while( 1 ) |
8 | {
|
9 | rprintf("T0CR0:%i\n\r",YPacc); |
10 | }
|
And the result output is now :
1 | ADXL2148 Accelerometer Yp raw data : |
2 | T0CR0:4326756 |
3 | T0CR0:4325926 |
4 | T0CR0:4324216 |
5 | T0CR0:4324036 |
6 | T0CR0:4326626 |
7 | 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 :
1 | rprintf_devopen(putc_serial0); //Init rprintf |
2 | rprintf("ADXL2148 Accelerometer Yp raw data :\n\r"); |
3 | |
4 | while( 1 ) |
5 | {
|
6 | VICIntEnable |= TIMER0_INT; // Enable Timer0 Interrupts |
7 | T0TCR = 0x01; // TIMER0 Enable |
8 | delay_ms(20); // Do some acquisition |
9 | T0TCR = 0x00; // TIMER0 Disable |
10 | VICIntEnClr |= TIMER0_INT; // Stop Timer0 Interrupts |
11 | |
12 | result = T1/((T1+T2)/100); // Duty cycle calculation in percent |
13 | |
14 | if( (result > (oldresult+1)) || (result < (oldresult-1)) ) // If detect movement |
15 | {
|
16 | i=100; |
17 | rprintf("%d ", result ); |
18 | }
|
19 | |
20 | }
|
Interrupt section :
1 | static void ISR_Timer0(void) |
2 | {
|
3 | //Interrupt Code Here
|
4 | T0TCR = 0x02; // TIMER0 Disable; reset T0TC & T0PC |
5 | T0PR = 0x00000000; // Reset T0PR |
6 | |
7 | if(state) |
8 | {
|
9 | T1 = T0CR0; |
10 | T0CCR = 0x06; // Capture on CAPn.0 falling edge and Interrupt on CAPn.0 event |
11 | state = 0; |
12 | }
|
13 | else
|
14 | {
|
15 | T2 = T0CR0; |
16 | T0CCR = 0x05; // Capture on CAPn.0 rising edge and Interrupt on CAPn.0 event |
17 | state = 1; |
18 | }
|
19 | |
20 | T0IR = 0xFF; //Clear the timer interrupt |
21 | T0TCR = 0x01; // TIMER0 Enable |
22 | |
23 | VICVectAddr =0; //Update the VIC priorities |
24 | }
|
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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