/**
* @brief Enables a PWM channel.
* @pre The PWM unit must have been activated using @p pwmStart().
* @post The channel is active using the specified configuration.
* @note The function has effect at the next cycle start.
* @note Channel notification is not enabled.
*
* @param[in] pwmp pointer to a @p PWMDriver object
* @param[in] channel PWM channel identifier (0...channels-1)
* @param[in] width PWM pulse width as clock pulses number
*
* @notapi
*/
void pwm_lld_enable_channel(PWMDriver *pwmp,
pwmchannel_t channel,
pwmcnt_t width) {
#if NRF5_PWM_USE_GPIOTE_PPI
const PWMChannelConfig *cfg_channel = &pwmp->config->channels[channel];
const uint8_t gpiote_channel = cfg_channel->gpiote_channel;
const uint8_t *ppi_channel = cfg_channel->ppi_channel;
uint32_t outinit;
switch(cfg_channel->mode & PWM_OUTPUT_MASK) {
case PWM_OUTPUT_ACTIVE_LOW : outinit = GPIOTE_CONFIG_OUTINIT_Low; break;
case PWM_OUTPUT_ACTIVE_HIGH: outinit = GPIOTE_CONFIG_OUTINIT_High; break;
case PWM_OUTPUT_DISABLED : /* fall-through */
default : goto no_output_config;
}
/* Deal with corner case: 0% and 100% */
if ((width <= 0) || (width >= pwmp->period)) {
/* Disable GPIOTE/PPI task */
NRF_GPIOTE->CONFIG[gpiote_channel] = GPIOTE_CONFIG_MODE_Disabled;
NRF_PPI->CHENCLR = ((1 << ppi_channel[0]) | (1 << ppi_channel[1]));
/* Set Line */
palWriteLine(cfg_channel->ioline,
((width <= 0) ^
((cfg_channel->mode & PWM_OUTPUT_MASK) == PWM_OUTPUT_ACTIVE_HIGH)));
/* Really doing PWM */
} else {
const uint32_t gpio_pin = PAL_PAD(cfg_channel->ioline);
const uint32_t polarity = GPIOTE_CONFIG_POLARITY_Toggle;
/* Program tasks (one for duty cycle, one for periode) */
NRF_PPI->CH[ppi_channel[0]].EEP =
(uint32_t)&pwmp->timer->EVENTS_COMPARE[channel];
NRF_PPI->CH[ppi_channel[0]].TEP =
(uint32_t)&NRF_GPIOTE->TASKS_OUT[gpiote_channel];
NRF_PPI->CH[ppi_channel[1]].EEP =
(uint32_t)&pwmp->timer->EVENTS_COMPARE[pwmp->channels];
NRF_PPI->CH[ppi_channel[1]].TEP =
(uint32_t)&NRF_GPIOTE->TASKS_OUT[gpiote_channel];
NRF_PPI->CHENSET = ((1 << ppi_channel[0]) | (1 << ppi_channel[1]));
/* Something Old, something New */
const uint32_t old_width = pwmp->timer->CC[channel];
const uint32_t new_width = width;
/* Check GPIOTE state */
const bool gpiote = (NRF_GPIOTE->CONFIG[gpiote_channel] &
GPIOTE_CONFIG_MODE_Msk) != GPIOTE_CONFIG_MODE_Disabled;
/* GPIOTE is currently running */
if (gpiote) {
uint32_t current;
while (true) {
pwmp->timer->TASKS_CAPTURE[PWM_GPIOTE_PPI_CC] = 1;
current = pwmp->timer->CC[PWM_GPIOTE_PPI_CC];
if (pwm_within_safe_margins(pwmp, current, old_width) &&
pwm_within_safe_margins(pwmp, current, new_width))
break;
}
if (((old_width <= current) && (current < new_width)) ||
((new_width <= current) && (current < old_width))) {
NRF_GPIOTE->TASKS_OUT[gpiote_channel] = 1;
}
/* GPIOTE need to be restarted */
} else {
/* Create GPIO Task */
NRF_GPIOTE->CONFIG[gpiote_channel] =
(GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos) |
((gpio_pin << GPIOTE_CONFIG_PSEL_Pos ) & GPIOTE_CONFIG_PSEL_Msk )|
((polarity << GPIOTE_CONFIG_POLARITY_Pos) & GPIOTE_CONFIG_POLARITY_Msk)|
((outinit << GPIOTE_CONFIG_OUTINIT_Pos ) & GPIOTE_CONFIG_OUTINIT_Msk );
pwmp->timer->TASKS_CAPTURE[PWM_GPIOTE_PPI_CC] = 1;
if (pwmp->timer->CC[PWM_GPIOTE_PPI_CC] > width)
NRF_GPIOTE->TASKS_OUT[gpiote_channel] = 1;
}
}
no_output_config:
#endif
pwmp->timer->CC[channel] = width;
}
static void sp100_spi_start(int n) {
spi_cfg.ssport = PAL_PORT(sp100_ss[n]);
spi_cfg.sspad = PAL_PAD(sp100_ss[n]);
spiStart(sp100_spid, &spi_cfg);
}
