/**
* \brief Configures the DAC in event triggered mode.
*
* Configures the DAC to use the module's default configuration, with output
* channel mode configured for event triggered conversions.
*
* \param dev_inst Pointer to the DAC module software instance to initialize
*/
static void configure_dac(struct dac_module *dac_module)
{
struct dac_config config;
struct dac_chan_config channel_config;
/* Get the DAC default configuration */
dac_get_config_defaults(&config);
/* Switch to GCLK generator 0 */
config.clock_source = GCLK_GENERATOR_0;
dac_init(dac_module, DAC, &config);
/* Get the default DAC channel config */
dac_chan_get_config_defaults(&channel_config);
/* Set the channel configuration, and enable it */
dac_chan_set_config(dac_module, DAC_CHANNEL_0, &channel_config);
dac_chan_enable(dac_module, DAC_CHANNEL_0);
/* Enable event triggered conversions */
struct dac_events events = { .on_event_start_conversion = true };
dac_enable_events(dac_module, &events);
dac_enable(dac_module);
}
/**
* \brief Configures the TC to generate output events at the sample frequency.
*
* Configures the TC in Frequency Generation mode, with an event output once
* each time the audio sample frequency period expires.
*
* \param dev_inst Pointer to the TC module software instance to initialize
*/
static void configure_tc(struct tc_module *tc_module)
{
struct tc_config config;
tc_get_config_defaults(&config);
config.clock_source = GCLK_GENERATOR_0;
config.wave_generation = TC_WAVE_GENERATION_MATCH_FREQ;
tc_init(tc_module, TC3, &config);
/* Enable periodic event output generation */
struct tc_events events = { .generate_event_on_overflow = true };
tc_enable_events(tc_module, &events);
/* Set the timer top value to alter the overflow frequency */
tc_set_top_value(tc_module,
system_gclk_gen_get_hz(GCLK_GENERATOR_0) / sample_rate);
tc_enable(tc_module);
}
/**
* \brief Configures the event system to link the sample timer to the DAC.
*
* Configures the event system, linking the TC module used for the audio sample
* rate timing to the DAC, so that a new conversion is triggered each time the
* DAC receives an event from the timer.
*/
static void configure_events(struct events_resource *event)
{
struct events_config config;
events_get_config_defaults(&config);
config.generator = EVSYS_ID_GEN_TC3_OVF;
config.path = EVENTS_PATH_ASYNCHRONOUS;
events_allocate(event, &config);
events_attach_user(event, EVSYS_ID_USER_DAC_START);
}
/**
* \brief Main application routine
*/
int main(void)
{
struct dac_module dac_module;
struct tc_module tc_module;
struct events_resource event;
/* Initialize all the system clocks, pm, gclk... */
system_init();
/* Enable the internal bandgap to use as reference to the DAC */
system_voltage_reference_enable(SYSTEM_VOLTAGE_REFERENCE_BANDGAP);
/* Module configuration */
configure_tc(&tc_module);
configure_dac(&dac_module);
configure_events(&event);
/* Start the sample trigger timer */
tc_start_counter(&tc_module);
while (true) {
while (port_pin_get_input_level(SW0_PIN) == SW0_INACTIVE) {
/* Wait for the button to be pressed */
}
port_pin_toggle_output_level(LED0_PIN);
for (uint32_t i = 0; i < number_of_samples; i++) {
dac_chan_write(&dac_module, DAC_CHANNEL_0, wav_samples[i]);
while (!(DAC->INTFLAG.reg & DAC_INTFLAG_EMPTY)) {
/* Wait for data buffer to be empty */
}
}
while (port_pin_get_input_level(SW0_PIN) == SW0_ACTIVE) {
/* Wait for the button to be depressed */
}
}
}
//! [setup_dac]
void configure_dac(void)
{
//! [setup_dac_config]
struct dac_config config_dac;
//! [setup_dac_config]
//! [setup_dac_config_default]
dac_get_config_defaults(&config_dac);
//! [setup_dac_config_default]
//! [setup_dac_start_on_event]
#if (SAML21)
dac_instance.start_on_event[DAC_CHANNEL_0] = true;
#else
dac_instance.start_on_event = true;
#endif
//! [setup_dac_start_on_event]
//! [setup_dac_instance]
dac_init(&dac_instance, DAC, &config_dac);
//! [setup_dac_instance]
//! [setup_dac_on_event_start_conversion]
struct dac_events events =
#if (SAML21)
{ .on_event_chan0_start_conversion = true };
#else
{ .on_event_start_conversion = true };
#endif
//! [setup_dac_on_event_start_conversion]
//! [enable_dac_event]
dac_enable_events(&dac_instance, &events);
//! [enable_dac_event]
}
//! [setup_dac]
//! [setup_dac_channel]
void configure_dac_channel(void)
{
//! [setup_dac_chan_config]
struct dac_chan_config config_dac_chan;
//! [setup_dac_chan_config]
//! [setup_dac_chan_config_default]
dac_chan_get_config_defaults(&config_dac_chan);
//! [setup_dac_chan_config_default]
//! [set_dac_chan_config]
dac_chan_set_config(&dac_instance, DAC_CHANNEL_0,
&config_dac_chan);
//! [set_dac_chan_config]
//! [enable_dac_channel]
dac_chan_enable(&dac_instance, DAC_CHANNEL_0);
//! [enable_dac_channel]
}
//! [setup_dac_channel]
int main(void)
{
//! [data_length_var]
uint32_t i;
//! [data_length_var]
system_init();
//! [setup_init]
//! [init_rtc]
configure_rtc_count();
//! [init_rtc]
//! [set_rtc_period]
rtc_count_set_period(&rtc_instance, 1);
//! [set_rtc_period]
//! [init_dac]
configure_dac();
//! [init_dac]
//! [init_dac_chan]
configure_dac_channel();
//! [init_dac_chan]
//! [enable_dac]
dac_enable(&dac_instance);
//! [enable_dac]
//! [init_event_resource]
configure_event_resource();
//! [init_event_resource]
//! [register_dac_callback]
dac_register_callback(&dac_instance, DAC_CHANNEL_0,
dac_callback,DAC_CALLBACK_TRANSFER_COMPLETE);
//! [register_dac_callback]
//! [enable_dac_callback]
dac_chan_enable_callback(&dac_instance, DAC_CHANNEL_0,
DAC_CALLBACK_TRANSFER_COMPLETE);
//! [enable_dac_callback]
//! [setup_dac_data]
for (i = 0;i < DATA_LENGTH;i++) {
dac_data[i] = 0xfff * i;
}
//! [setup_dac_data]
//! [setup_init]
//! [main_start]
//! [main_write]
dac_chan_write_buffer_job(&dac_instance, DAC_CHANNEL_0,
dac_data, DATA_LENGTH);
//! [main_write]
//! [main_check_transfer_done]
while (!transfer_is_done) {
/* Wait for transfer done */
}
//! [main_check_transfer_done]
//! [main_loop]
while (1) {
}
//! [main_loop]
//! [main_start]
}
/* Timer 0 Initialization */
void timer_init(void)
{
struct tc_config conf_tc;
struct tc_events conf_tc_events = {.generate_event_on_compare_channel[0] = 1};
tc_get_config_defaults(&conf_tc);
conf_tc.clock_source = GCLK_GENERATOR_0;
conf_tc.wave_generation = TC_WAVE_GENERATION_MATCH_FREQ;
conf_tc.counter_16_bit.compare_capture_channel[0] = 0xFFFF;
tc_init(&tc_inst, TC0, &conf_tc);
tc_enable_events(&tc_inst, &conf_tc_events);
tc_enable(&tc_inst);
tc_stop_counter(&tc_inst);
/* Enable TC0 match/capture channel 0 interrupt */
TC0->COUNT16.INTENSET.bit.MC0 = 1;
/* Enable TC0 module interrupt */
NVIC_EnableIRQ(TC0_IRQn);
}
/* DAC Initialization */
void dac_initialize(void)
{
struct dac_config conf_dac;
struct dac_events conf_dac_events = {.on_event_start_conversion = 1};
dac_get_config_defaults(&conf_dac);
conf_dac.clock_source = GCLK_GENERATOR_3;
conf_dac.reference = DAC_REFERENCE_INT1V;
dac_init(&dac_inst, DAC, &conf_dac);
dac_enable_events(&dac_inst, &conf_dac_events);
dac_enable(&dac_inst);
}
/* Event System Initialization */
void evsys_init(void)
{
struct events_resource conf_event_resource;
struct events_config conf_event;
events_get_config_defaults(&conf_event);
conf_event.edge_detect = EVENTS_EDGE_DETECT_NONE;
conf_event.path = EVENTS_PATH_ASYNCHRONOUS;
conf_event.generator = EVSYS_ID_GEN_TC0_MCX_0;
events_allocate(&conf_event_resource, &conf_event);
events_attach_user(&conf_event_resource, EVSYS_ID_USER_DAC_START);
}
/* Initialize the selected waveform buffer with output data */
void buffer_init(void)
{
#if WAVE_MODE==SINE_WAVE
for (i = 0; i < DEGREES_PER_CYCLE; i++) {
sine_wave_buf[i] = (uint16_t)(500 + (500*sin((double)i*DEGREE)));
}
#elif WAVE_MODE==SAW_TOOTH_WAVE
for (i = 0; i < 256; i++) {
sawtooth_wave_buf[i] = i*4;
}
#elif WAVE_MODE==TRIANGLE_WAVE
for (i = 0; i < 128; i++) {
triangle_wave_buf[i] = i*8;
}
for (i = 128; i < 256; i++) {
triangle_wave_buf[i] = 1023 - (i*8);
}
#endif
}
/* Main function */
int main(void)
{
system_init();
timer_init();
dac_initialize();
evsys_init();
buffer_init();
/* Set the TC0 compare value corresponding to specified frequency */
#if WAVE_MODE==SINE_WAVE
tc_set_compare_value(&tc_inst, 0, \
system_gclk_gen_get_hz(GCLK_GENERATOR_0)/(FREQUENCY*360));
#else
tc_set_compare_value(&tc_inst, 0, \
system_gclk_gen_get_hz(GCLK_GENERATOR_0)/(FREQUENCY*256));
#endif
/* Start TC0 timer */
tc_start_counter(&tc_inst);
/* Enable global interrupt */
system_interrupt_enable_global();
while (true) {
}
}
