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/*
ChibiOS/HAL - Copyright (C) 2016 Stéphane D'Alu
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
/**
* @file hal_pwm_lld.c
* @brief NRF51 PWM subsystem low level driver source.
*
* @note Using the method described in nrf51-pwm-library to correctly
* handle toggling of the pin with GPIOTE when changing period.
* It means it is generally unsafe to use GPIOTE with a period
* less than (2 * PWM_GPIOTE_DECISION_TIME / 16MHz)
*
* @addtogroup PWM
* @{
*/
#include "hal.h"
#if HAL_USE_PWM || defined(__DOXYGEN__)
/*===========================================================================*/
/* Driver local definitions. */
/*===========================================================================*/
#define PWM_GPIOTE_PPI_CC 3
#define PWM_GPIOTE_DECISION_TIME 160
/*===========================================================================*/
/* Driver exported variables. */
/*===========================================================================*/
/**
* @brief PWMD1 driver identifier.
* @note The driver PWMD1 allocates the timer TIMER0 when enabled.
*/
#if NRF5_PWM_USE_TIMER0 || defined(__DOXYGEN__)
PWMDriver PWMD1;
#endif
/**
* @brief PWMD2 driver identifier.
* @note The driver PWMD2 allocates the timer TIMER1 when enabled.
*/
#if NRF5_PWM_USE_TIMER1 || defined(__DOXYGEN__)
PWMDriver PWMD2;
#endif
/**
* @brief PWMD3 driver identifier.
* @note The driver PWMD3 allocates the timer TIMER2 when enabled.
*/
#if NRF5_PWM_USE_TIMER2 || defined(__DOXYGEN__)
PWMDriver PWMD3;
#endif
/*===========================================================================*/
/* Driver local variables and types. */
/*===========================================================================*/
static const uint8_t pwm_margin_by_prescaler[] = {
(PWM_GPIOTE_DECISION_TIME + 0) >> 0,
(PWM_GPIOTE_DECISION_TIME + 1) >> 1,
(PWM_GPIOTE_DECISION_TIME + 3) >> 2,
(PWM_GPIOTE_DECISION_TIME + 7) >> 3,
(PWM_GPIOTE_DECISION_TIME + 15) >> 4,
(PWM_GPIOTE_DECISION_TIME + 31) >> 5,
(PWM_GPIOTE_DECISION_TIME + 63) >> 6,
(PWM_GPIOTE_DECISION_TIME + 127) >> 7,
(PWM_GPIOTE_DECISION_TIME + 255) >> 8,
(PWM_GPIOTE_DECISION_TIME + 511) >> 9
};
/*===========================================================================*/
/* Driver local functions. */
/*===========================================================================*/
static void pwm_lld_serve_interrupt(PWMDriver *pwmp) {
uint8_t channel;
/* Deal with PWM channels
*/
for (channel = 0 ; channel < pwmp->channels ; channel++) {
if (pwmp->timer->EVENTS_COMPARE[channel]) {
pwmp->timer->EVENTS_COMPARE[channel] = 0;
if (pwmp->config->channels[channel].callback != NULL) {
pwmp->config->channels[channel].callback(pwmp);
}
}
}
/* Deal with PWM period
*/
if (pwmp->timer->EVENTS_COMPARE[pwmp->channels]) {
pwmp->timer->EVENTS_COMPARE[pwmp->channels] = 0;
if (pwmp->config->callback != NULL) {
pwmp->config->callback(pwmp);
}
}
}
static inline
bool pwm_within_safe_margins(PWMDriver *pwmp, uint32_t timer, uint32_t width) {
const uint32_t margin = pwm_margin_by_prescaler[pwmp->timer->PRESCALER];
return (width <= margin)
? ((width <= timer) && (timer < (pwmp->period + width - margin)))
: ((width <= timer) || (timer < (width - margin)));
}
/*===========================================================================*/
/* Driver interrupt handlers. */
/*===========================================================================*/
#if NRF5_PWM_USE_TIMER0
/**
* @brief TIMER0 interrupt handler.
*
* @isr
*/
OSAL_IRQ_HANDLER(Vector60) {
OSAL_IRQ_PROLOGUE();
pwm_lld_serve_interrupt(&PWMD1);
OSAL_IRQ_EPILOGUE();
}
#endif /* NRF5_PWM_USE_TIMER0 */
#if NRF5_PWM_USE_TIMER1
/**
* @brief TIMER1 interrupt handler.
*
* @isr
*/
OSAL_IRQ_HANDLER(Vector64) {
OSAL_IRQ_PROLOGUE();
pwm_lld_serve_interrupt(&PWMD2);
OSAL_IRQ_EPILOGUE();
}
#endif /* NRF5_PWM_USE_TIMER1 */
#if NRF5_PWM_USE_TIMER2
/**
* @brief TIMER2 interrupt handler.
*
* @isr
*/
OSAL_IRQ_HANDLER(Vector68) {
OSAL_IRQ_PROLOGUE();
pwm_lld_serve_interrupt(&PWMD3);
OSAL_IRQ_EPILOGUE();
}
#endif /* NRF5_PWM_USE_TIMER2 */
/*===========================================================================*/
/* Driver exported functions. */
/*===========================================================================*/
/**
* @brief Low level PWM driver initialization.
*
* @notapi
*/
void pwm_lld_init(void) {
#if NRF5_PWM_USE_TIMER0
pwmObjectInit(&PWMD1);
PWMD1.channels = PWM_CHANNELS;
PWMD1.timer = NRF_TIMER0;
#endif
#if NRF5_PWM_USE_TIMER1
pwmObjectInit(&PWMD2);
PWMD2.channels = PWM_CHANNELS;
PWMD2.timer = NRF_TIMER1;
#endif
#if NRF5_PWM_USE_TIMER2
pwmObjectInit(&PWMD3);
PWMD3.channels = PWM_CHANNELS;
PWMD3.timer = NRF_TIMER2;
#endif
}
/**
* @brief Configures and activates the PWM peripheral.
* @note Starting a driver that is already in the @p PWM_READY state
* disables all the active channels.
*
* @param[in] pwmp pointer to a @p PWMDriver object
*
* @notapi
*/
void pwm_lld_start(PWMDriver *pwmp) {
/* Prescaler value calculation: ftimer = 16MHz / 2^PRESCALER */
uint16_t psc_ratio = NRF5_HFCLK_FREQUENCY / pwmp->config->frequency;
/* Prescaler ratio must be between 1 and 512, and a power of two. */
osalDbgAssert(psc_ratio <= 512 && !(psc_ratio & (psc_ratio - 1)),
"invalid frequency");
/* Prescaler value as a power of 2, must be 0..9 */
uint32_t psc_value;
for (psc_value = 0; psc_value < 10; psc_value++)
if (psc_ratio == (unsigned)(1 << psc_value))
break;
/* Configure as 16bits timer (only TIMER0 support 32bits) */
pwmp->timer->BITMODE = TIMER_BITMODE_BITMODE_16Bit;
pwmp->timer->MODE = TIMER_MODE_MODE_Timer;
/* With clear shortcuts for period */
pwmp->timer->SHORTS =
0x1UL << (TIMER_SHORTS_COMPARE0_CLEAR_Pos + pwmp->channels);
/* Disable and reset interrupts for compare events */
pwmp->timer->INTENCLR = (TIMER_INTENCLR_COMPARE0_Msk |
TIMER_INTENCLR_COMPARE1_Msk |
TIMER_INTENCLR_COMPARE2_Msk |
TIMER_INTENCLR_COMPARE3_Msk );
pwmp->timer->EVENTS_COMPARE[0] = 0;
pwmp->timer->EVENTS_COMPARE[1] = 0;
pwmp->timer->EVENTS_COMPARE[2] = 0;
pwmp->timer->EVENTS_COMPARE[3] = 0;
/* Set prescaler */
pwmp->timer->PRESCALER = psc_value;
/* Set period */
pwmp->timer->CC[pwmp->channels] = pwmp->period;
/* Clear everything */
pwmp->timer->TASKS_CLEAR = 1;
/* Enable interrupt */
#if NRF5_PWM_USE_TIMER0
if (&PWMD1 == pwmp) {
nvicEnableVector(TIMER0_IRQn, NRF5_PWM_TIMER0_PRIORITY);
}
#endif
#if NRF5_PWM_USE_TIMER1
if (&PWMD2 == pwmp) {
nvicEnableVector(TIMER1_IRQn, NRF5_PWM_TIMER1_PRIORITY);
}
#endif
#if NRF5_PWM_USE_TIMER2
if (&PWMD3 == pwmp) {
nvicEnableVector(TIMER2_IRQn, NRF5_PWM_TIMER2_PRIORITY);
}
#endif
/* Start timer */
pwmp->timer->TASKS_START = 1;
}
/**
* @brief Deactivates the PWM peripheral.
*
* @param[in] pwmp pointer to a @p PWMDriver object
*
* @notapi
*/
void pwm_lld_stop(PWMDriver *pwmp) {
pwmp->timer->TASKS_SHUTDOWN = 1;
#if NRF5_PWM_USE_TIMER0
if (&PWMD1 == pwmp) {
nvicDisableVector(TIMER0_IRQn);
}
#endif
#if NRF5_PWM_USE_TIMER1
if (&PWMD2 == pwmp) {
nvicDisableVector(TIMER1_IRQn);
}
#endif
#if NRF5_PWM_USE_TIMER2
if (&PWMD3 == pwmp) {
nvicDisableVector(TIMER2_IRQn);
}
#endif
}
/**
* @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;
}
/**
* @brief Disables a PWM channel and its notification.
* @pre The PWM unit must have been activated using @p pwmStart().
* @post The channel is disabled and its output line returned to the
* idle state.
* @note The function has effect at the next cycle start.
*
* @param[in] pwmp pointer to a @p PWMDriver object
* @param[in] channel PWM channel identifier (0...channels-1)
*
* @notapi
*/
void pwm_lld_disable_channel(PWMDriver *pwmp, pwmchannel_t channel) {
pwmp->timer->CC[channel] = 0;
#if NRF5_PWM_USE_GPIOTE_PPI
const PWMChannelConfig *cfg_channel = &pwmp->config->channels[channel];
switch(cfg_channel->mode & PWM_OUTPUT_MASK) {
case PWM_OUTPUT_ACTIVE_LOW:
case PWM_OUTPUT_ACTIVE_HIGH: {
const uint8_t gpiote_channel = cfg_channel->gpiote_channel;
const uint8_t *ppi_channel = cfg_channel->ppi_channel;
NRF_PPI->CHENCLR = ((1 << ppi_channel[0]) | (1 << ppi_channel[1]));
NRF_GPIOTE->CONFIG[gpiote_channel] = GPIOTE_CONFIG_MODE_Disabled;
break;
}
case PWM_OUTPUT_DISABLED:
default:
break;
}
#endif
}
/**
* @brief Enables the periodic activation edge notification.
* @pre The PWM unit must have been activated using @p pwmStart().
* @note If the notification is already enabled then the call has no effect.
*
* @param[in] pwmp pointer to a @p PWMDriver object
*
* @notapi
*/
void pwm_lld_enable_periodic_notification(PWMDriver *pwmp) {
pwmp->timer->INTENSET =
0x1UL << (TIMER_INTENSET_COMPARE0_Pos + pwmp->channels);
}
/**
* @brief Disables the periodic activation edge notification.
* @pre The PWM unit must have been activated using @p pwmStart().
* @note If the notification is already disabled then the call has no effect.
*
* @param[in] pwmp pointer to a @p PWMDriver object
*
* @notapi
*/
void pwm_lld_disable_periodic_notification(PWMDriver *pwmp) {
pwmp->timer->INTENCLR =
0x1UL << (TIMER_INTENCLR_COMPARE0_Pos + pwmp->channels);
}
/**
* @brief Enables a channel de-activation edge notification.
* @pre The PWM unit must have been activated using @p pwmStart().
* @pre The channel must have been activated using @p pwmEnableChannel().
* @note If the notification is already enabled then the call has no effect.
*
* @param[in] pwmp pointer to a @p PWMDriver object
* @param[in] channel PWM channel identifier (0...channels-1)
*
* @notapi
*/
void pwm_lld_enable_channel_notification(PWMDriver *pwmp,
pwmchannel_t channel) {
pwmp->timer->INTENSET =
0x1UL << (TIMER_INTENSET_COMPARE0_Pos + channel);
}
/**
* @brief Disables a channel de-activation edge notification.
* @pre The PWM unit must have been activated using @p pwmStart().
* @pre The channel must have been activated using @p pwmEnableChannel().
* @note If the notification is already disabled then the call has no effect.
*
* @param[in] pwmp pointer to a @p PWMDriver object
* @param[in] channel PWM channel identifier (0...channels-1)
*
* @notapi
*/
void pwm_lld_disable_channel_notification(PWMDriver *pwmp,
pwmchannel_t channel) {
pwmp->timer->INTENCLR =
0x1UL << (TIMER_INTENCLR_COMPARE0_Pos + channel);
}
#endif /* HAL_USE_PWM */
/** @} */
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