Hello,
In first, i want to apology because my English is not good, so please don't tease me...
My project is base on the use of internal and external clocks and command 3 digital output pins to command a sequence in a multiplexer 8 to 1. I create PWM signal with a frequency max 2,5 Mhz and min 217 KHz. With another interruption timer, i change the output on the multiplexer every 10 KHz.
In the beginning, i choose the DUE card because of the 9 timers. But after some tests and research, i think this card it's not really good for this job. And the first reason is this table :
| Instance | TCX | Channel | External Clock | Input pin | Internal clock | output pin |
|---|---|---|---|---|---|---|
| T0 | TC0 | 0 | XC0 | pin 22 | TCLK0 | Pin 2 |
| T1 | TC0 | 1 | XC0 | Ana In5 | TCLK1 | Ana In7 |
| T2 | TC0 | 2 | XC0 | pin 31 | TCLK2 | / |
| T3 | TC1 | 0 | XC1 | Ana In3 | TCLK3 | / |
| T4 | TC1 | 1 | XC1 | Ana In2 | TCLK4 | / |
| T5 | TC1 | 2 | XC1 | DAC1 | TCLK5 | / |
| T6 | TC2 | 0 | XC2 | / | TCLK6 | pin 5 |
| T7 | TC2 | 1 | XC2 | LED "RX" | TCLK7 | Pin 3 |
| T8 | TC2 | 2 | XC2 | pin 30 | TCLK8 | Pin 11 |
Like i understand this, if you want to use an external clock to create a PWM signal, you can use only the timer0 and timer8. All the other have not hardware connection for a external clock (timer6 and timer7) or a hardware output (timer1, timer2, timer3, timer4 and timer5). So, in first you have 9 timers and in the end you can use only 2 ! (or 4 with internal clock)
In the first place, when i want to comprehend the DUE board, i create 4 PWM signals with internal clock only (timer0, timer6, timer7 and timer8) because they have hardware connection output.
void setup()
{
//Declaration des sorties PWM
pinMode (2, OUTPUT);
pinMode (3, OUTPUT);
pinMode (5, OUTPUT);
pinMode (11, OUTPUT);
/*Initialisation périfiques du timers 0, 6, 7, 8 */
pmc_set_writeprotect(false); //Turn off write protection on Power Management Controller
pmc_enable_periph_clk(TC0_IRQn); // Enable the peripheral clock by IRQ for Timer 0 channel 0
pmc_enable_periph_clk(TC6_IRQn); // Enable the peripheral clock by IRQ for Timer 2 channel 0
pmc_enable_periph_clk(TC7_IRQn); // Enable the peripheral clock by IRQ for Timer 2 channel 1
pmc_enable_periph_clk(TC8_IRQn); // Enable the peripheral clock by IRQ for Timer 2 channel 2
/* Configuration du timer TC2 channel 0 => timer 6 */
TcChannel * t6 = &(TC2->TC_CHANNEL)[0] ; // creation du pointeur sur le registre TC0 channel 0
t6->TC_CCR = TC_CCR_CLKDIS ; // désactivation des horloges le temps des reglages
t6->TC_IDR = 0xFFFFFFFF ; // desactivation des interruptions
t6->TC_SR ; // lecture status pour reinitialisation du timer
t6->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK1 | // utilisation TCLK1 (division par 2, F = 42MHz)
TC_CMR_WAVE | // mode courbe
TC_CMR_WAVSEL_UP_RC | // compteur PWM utilisant le registre RC
TC_CMR_ACPA_CLEAR | TC_CMR_ACPC_CLEAR |
TC_CMR_BCPB_CLEAR | TC_CMR_BCPC_CLEAR ;
t6->TC_RC = 42; // Definition de la fréquence : 42 MHz / TC_RC
t6->TC_RA = 21; // Definition du rapport cyclique, avec RA = 1/2 RC
t6->TC_CMR = (t6->TC_CMR & 0xFFF0FFFF) | TC_CMR_ACPA_CLEAR | TC_CMR_ACPC_SET ; // set et reset des flags pour la comparaison des registres RA et RC
t6->TC_CCR = TC_CCR_CLKEN | TC_CCR_SWTRG ; // reactivation de l horloge.
/* Configuration des I/O : */
int ulPin6 = 5; // Timer6 -> PWM Pin 5
PIO_Configure(g_APinDescription[ulPin6].pPort,
g_APinDescription[ulPin6].ulPinType,
g_APinDescription[ulPin6].ulPin,
g_APinDescription[ulPin6].ulPinConfiguration);
/* Configuration du timer TC0 channel 0 => timer 0 */
TcChannel * t0 = &(TC0->TC_CHANNEL)[0] ; // creation du pointeur sur le registre TC0 channel 0
t0->TC_CCR = TC_CCR_CLKDIS ; // désactivation des horloges le temps des reglages
t0->TC_IDR = 0xFFFFFFFF ; // desactivation des interruptions
t0->TC_SR ; // lecture status pour reinitialisation du timer
t0->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK1 | // utilisation TCLK1 (division par 2, F = 42MHz)
TC_CMR_WAVE | // mode courbe
TC_CMR_WAVSEL_UP_RC | // compteur PWM utilisant le registre RC
TC_CMR_ACPA_CLEAR | TC_CMR_ACPC_CLEAR |
TC_CMR_BCPB_CLEAR | TC_CMR_BCPC_CLEAR ;
t0->TC_RC = 17; // Definition de la fréquence : 42 MHz / TC_RC
t0->TC_RA = 8; // Definition du rapport cyclique, avec RA = 1/2 RC
t0->TC_CMR = (t0->TC_CMR & 0xFFF0FFFF) | TC_CMR_ACPA_CLEAR | TC_CMR_ACPC_SET ; // set et reset des flags pour la comparaison des registres RA et RC
t0->TC_CCR = TC_CCR_CLKEN | TC_CCR_SWTRG ; // reactivation de l horloge.
int ulPin0 = 2; // Timer0 -> PWM Pin 2
PIO_Configure(g_APinDescription[ulPin0].pPort,
g_APinDescription[ulPin0].ulPinType,
g_APinDescription[ulPin0].ulPin,
g_APinDescription[ulPin0].ulPinConfiguration);
}
void loop()
{
}
With this code, i have my 4 signals with the correct frequency i set.