//Config PA1 as an PWM output pin
void initPWM()
{
//Timer is 16Mhz
/* Enable module clock for the GPTx in Active mode, GPT0 clock enable, CPU running */
REG(SYS_CTRL_RCGCGPT) |= SYS_CTRL_RCGCGPT_GPT0;
disable_gptimer();
/* Use 16-bit timer */
REG(GPT_CONF_BASE + GPTIMER_CFG) = 0x04;
/* Configure PWM mode, 0x00000008 Timer A alternate mode. */
REG(GPT_CONF_BASE + GPTIMER_TAMR) = 0;
REG(GPT_CONF_BASE + GPTIMER_TAMR) |= GPTIMER_TAMR_TAAMS;
/* To enable PWM mode, the TACM bit must be cleared and the lowest 2 bits
(TAMR) field must be configured to 0x2.
GPTIMER_TnMR bit values, GPTIMER_TAMR_TAMR_PERIODIC is 0x00000002 */
REG(GPT_CONF_BASE + GPTIMER_TAMR) |= GPTIMER_TAMR_TAMR_PERIODIC;
//how often the counter is incremented: every pre-scaler / clock 16000000 seconds
REG(GPT_CONF_BASE + GPTIMER_TAPR) = 0; //PRESCALER_VALUE
/* Set the start value (period), count down */
REG(GPT_CONF_BASE+ GPTIMER_TAILR) = 16000; //frequency: 1kHz. 16000: 3E80, 16000000:F42400
/* Set the deassert period */
REG(GPT_CONF_BASE + GPTIMER_TAMATCHR) = 12800; //duty cycle: 20% so vibrator time is 20%. 800: 0x1F40, 8000000: 7A1200
// Defined in contiki/cpu/cc2538/dev/ioc.h
/* Function select for Port:Pin.
The third param sel can be any of the IOC_PXX_SEL_xyz defines.
For example, IOC_PXX_SEL_UART0_TXD will set the port to act as UART0 TX.
Selects one of the 32 pins on the four 8-pin I/O-ports (port A, port B, port C, and port D) to be the GPT0OCP1.
Configure pin : PA:1 selected as GPT0OCP1*/
ioc_set_sel(PWM_GPIO_CONF_PORT, PWM_GPIO_CONF_PIN, IOC_CONF_SEL);
/* Set Port:Pin override function, IOC_OVERRIDE_OE: Output */
ioc_set_over(PWM_GPIO_CONF_PORT, PWM_GPIO_CONF_PIN, IOC_OVERRIDE_OE);
/* Configure the pin to be under peripheral control with PIN_MASK of port with PORT_BASE.*/
GPIO_PERIPHERAL_CONTROL(GPIO_PORT_TO_BASE(PWM_GPIO_CONF_PORT), GPIO_PIN_MASK(PWM_GPIO_CONF_PIN));
enable_gptimer();
}
void pwm_disable(struct pwm_device *pwm)
{
disable_gptimer(pwm->id);
}
static void bfin_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bfin_pwm *priv = pwm_get_chip_data(pwm);
disable_gptimer(priv->pin);
}