/**
* \brief Retrieves the clock frequency of a Generic Clock generator.
*
* Determines the clock frequency (in Hz) of a specified Generic Clock
* generator, used as a source to a Generic Clock Channel module.
*
* \param[in] generator Generic Clock Generator index
*
* \return The frequency of the generic clock generator, in Hz.
*/
uint32_t system_gclk_gen_get_hz(
const uint8_t generator)
{
while (system_gclk_is_syncing(generator)) {
/* Wait for synchronization */
};
system_interrupt_enter_critical_section();
/* Get the frequency of the source connected to the GCLK generator */
uint32_t gen_input_hz = system_clock_source_get_hz(
(enum system_clock_source)GCLK->GENCTRL[generator].bit.SRC);
uint8_t divsel = GCLK->GENCTRL[generator].bit.DIVSEL;
uint32_t divider = GCLK->GENCTRL[generator].bit.DIV;
system_interrupt_leave_critical_section();
/* Check if the generator is using fractional or binary division */
if (!divsel && divider > 1) {
gen_input_hz /= divider;
} else if (divsel) {
gen_input_hz >>= (divider+1);
}
return gen_input_hz;
}
/**
* \brief Enables a Generic Clock Generator that was previously configured.
*
* Starts the clock generation of a Generic Clock Generator that was previously
* configured via a call to \ref system_gclk_gen_set_config().
*
* \param[in] generator Generic Clock Generator index to enable
*/
void system_gclk_gen_enable(
const uint8_t generator)
{
while (system_gclk_is_syncing()) {
/* Wait for synchronization */
};
system_interrupt_enter_critical_section();
/* Select the requested generator */
*((uint8_t*)&GCLK->GENCTRL.reg) = generator;
while (system_gclk_is_syncing()) {
/* Wait for synchronization */
};
/* Enable generator */
GCLK->GENCTRL.reg |= GCLK_GENCTRL_GENEN;
system_interrupt_leave_critical_section();
}
/**
* \brief Disables a Generic Clock Generator that was previously enabled.
*
* Stops the clock generation of a Generic Clock Generator that was previously
* started via a call to \ref system_gclk_gen_enable().
*
* \param[in] generator Generic Clock Generator index to disable
*/
void system_gclk_gen_disable(
const uint8_t generator)
{
while (system_gclk_is_syncing()) {
/* Wait for synchronization */
};
system_interrupt_enter_critical_section();
/* Select the requested generator */
*((uint8_t*)&GCLK->GENCTRL.reg) = generator;
while (system_gclk_is_syncing()) {
/* Wait for synchronization */
};
/* Disable generator */
GCLK->GENCTRL.reg &= ~GCLK_GENCTRL_GENEN;
while (GCLK->GENCTRL.reg & GCLK_GENCTRL_GENEN) {
/* Wait for clock to become disabled */
}
system_interrupt_leave_critical_section();
}
/**
* \brief Enables a Generic Clock Generator that was previously configured.
*
* Starts the clock generation of a Generic Clock Generator that was previously
* configured via a call to \ref system_gclk_gen_set_config().
*
* \param[in] generator Generic Clock Generator index to enable
*/
void system_gclk_gen_enable(
const uint8_t generator)
{
while (system_gclk_is_syncing(generator)) {
/* Wait for synchronization */
};
system_interrupt_enter_critical_section();
/* Enable generator */
GCLK->GENCTRL[generator].reg |= GCLK_GENCTRL_GENEN;
system_interrupt_leave_critical_section();
}
/**
* \brief Writes a Generic Clock Generator configuration to the hardware module.
*
* Writes out a given configuration of a Generic Clock Generator configuration
* to the hardware module.
*
* \note Changing the clock source on the fly (on a running
* generator) can take additional time if the clock source is configured
* to only run on-demand (ONDEMAND bit is set) and it is not currently
* running (no peripheral is requesting the clock source). In this case
* the GCLK will request the new clock while still keeping a request to
* the old clock source until the new clock source is ready.
*
* \note This function will not start a generator that is not already running;
* to start the generator, call \ref system_gclk_gen_enable()
* after configuring a generator.
*
* \param[in] generator Generic Clock Generator index to configure
* \param[in] config Configuration settings for the generator
*/
void system_gclk_gen_set_config(
const uint8_t generator,
struct system_gclk_gen_config *const config)
{
/* Sanity check arguments */
Assert(config);
/* Cache new register configurations to minimize sync requirements. */
uint32_t new_genctrl_config = (generator << GCLK_GENCTRL_ID_Pos);
uint32_t new_gendiv_config = (generator << GCLK_GENDIV_ID_Pos);
/* Select the requested source clock for the generator */
new_genctrl_config |= config->source_clock << GCLK_GENCTRL_SRC_Pos;
/* Configure the clock to be either high or low when disabled */
if (config->high_when_disabled) {
new_genctrl_config |= GCLK_GENCTRL_OOV;
}
/* Configure if the clock output to I/O pin should be enabled. */
if (config->output_enable) {
new_genctrl_config |= GCLK_GENCTRL_OE;
}
/* Set division factor */
if (config->division_factor > 1) {
/* Check if division is a power of two */
if (((config->division_factor & (config->division_factor - 1)) == 0)) {
/* Determine the index of the highest bit set to get the
* division factor that must be loaded into the division
* register */
uint32_t div2_count = 0;
uint32_t mask;
for (mask = (1UL << 1); mask < config->division_factor;
mask <<= 1) {
div2_count++;
}
/* Set binary divider power of 2 division factor */
new_gendiv_config |= div2_count << GCLK_GENDIV_DIV_Pos;
new_genctrl_config |= GCLK_GENCTRL_DIVSEL;
} else {
/* Set integer division factor */
new_gendiv_config |=
(config->division_factor) << GCLK_GENDIV_DIV_Pos;
/* Enable non-binary division with increased duty cycle accuracy */
new_genctrl_config |= GCLK_GENCTRL_IDC;
}
}
/* Enable or disable the clock in standby mode */
if (config->run_in_standby) {
new_genctrl_config |= GCLK_GENCTRL_RUNSTDBY;
}
while (system_gclk_is_syncing()) {
/* Wait for synchronization */
};
system_interrupt_enter_critical_section();
GCLK->GENDIV.reg = new_gendiv_config;
while (system_gclk_is_syncing()) {
/* Wait for synchronization */
};
GCLK->GENCTRL.reg = new_genctrl_config | (GCLK->GENCTRL.reg & GCLK_GENCTRL_GENEN);
system_interrupt_leave_critical_section();
}
