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pico-tracker/firmware/src/xosc.c

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/*
* Functions for controlling and calibrating against the external oscillator
* Copyright (C) 2015 Richard Meadows <richardeoin>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <string.h>
#include "samd20.h"
#include "system/clock.h"
#include "system/gclk.h"
#include "system/interrupt.h"
#include "system/pinmux.h"
#include "system/events.h"
#include "system/extint.h"
#include "tc/tc_driver.h"
#include "hw_config.h"
#include "xosc.h"
#include "watchdog.h"
enum measure_state_t {
MEASURE_WAIT_FOR_FIRST_EVENT,
MEASURE_MEASUREMENT,
} measure_state = MEASURE_WAIT_FOR_FIRST_EVENT;
enum xosc_measurement_t _measurement_t;
measurement_result_t _callback;
/**
* Configures external oscillator, waits for it to stabilise, and
* connects it to GLCK1.
*/
void xosc_init(void) {
#if USE_XOSC
system_clock_source_xosc_set_config(SYSTEM_CLOCK_EXTERNAL_CLOCK,
SYSTEM_XOSC_STARTUP_1,
true,
XOSC_FREQUENCY,
false,
false);
system_clock_source_enable(SYSTEM_CLOCK_SOURCE_XOSC);
while (!system_clock_source_is_ready(SYSTEM_CLOCK_SOURCE_XOSC));
#endif
/* Configure GCLK1 to XOSC */
system_gclk_gen_set_config(GCLK_GENERATOR_1,
#if USE_XOSC
GCLK_SOURCE_XOSC, /* Source */
#else
GCLK_SOURCE_OSC8M, /* Source */
#endif
false, /* High When Disabled */
XOSC_GCLK1_DIVIDE, /* Division Factor */
false, /* Run in standby */
false); /* Output Pin Enable */
/* Enable GCLK1 */
system_gclk_gen_enable(GCLK_GENERATOR_1);
}
struct osc8m_calibration_t osc8m_get_calibration(void) {
uint16_t calib_word = SYSCTRL->OSC8M.bit.CALIB;
struct osc8m_calibration_t calib;
calib.temperature = (calib_word >> 6) & 0x3F;
calib.process = (calib_word >> 0) & 0x3F;
return calib;
}
void osc8m_set_calibration(struct osc8m_calibration_t calib) {
uint16_t calib_word = ((calib.temperature & 0x3F) << 6) | (calib.process & 0x3F);
system_clock_source_write_calibration(SYSTEM_CLOCK_SOURCE_OSC8M, calib_word, 0x1);
}
/**
* Configure timer 4 to generate events at 1Hz of OSC8M
*/
/* void osc8m_event_source(void) { */
/* /\* Timer 4 runs on GCLK0 (4MHz) *\/ */
/* bool t4_capture_channel_enables[] = {false, false}; */
/* uint32_t t4_compare_channel_values[] = {15625, 0x0000}; */
/* /\* Divide by 256*15625 = 1Hz events *\/ */
/* tc_init(TC4, */
/* GCLK_GENERATOR_0, */
/* TC_COUNTER_SIZE_16BIT, */
/* TC_CLOCK_PRESCALER_DIV256, */
/* TC_WAVE_GENERATION_NORMAL_FREQ, */
/* TC_RELOAD_ACTION_GCLK, */
/* TC_COUNT_DIRECTION_UP, */
/* TC_WAVEFORM_INVERT_OUTPUT_NONE, */
/* false, /\* Oneshot *\/ */
/* false, /\* Run in standby *\/ */
/* 0x0000, /\* Initial value *\/ */
/* 0xFFFF, /\* Top value *\/ */
/* t4_capture_channel_enables, /\* Capture Channel Enables *\/ */
/* t4_compare_channel_values); /\* Compare Channels Values *\/ */
/* /\* Timer 4 generates an event on compare channel 0 *\/ */
/* struct tc_events events; */
/* events.generate_event_on_compare_channel[0] = true; */
/* events.generate_event_on_compare_channel[1] = false; */
/* events.generate_event_on_overflow = false; */
/* events.invert_event_input = false; */
/* events.on_event_perform_action = true; */
/* events.event_action = TC_EVENT_ACTION_RETRIGGER; */
/* tc_enable_events(TC4, &events); */
/* events_attach_user(0, 4); // Timer 4 is event user on channel 1 */
/* /\* This event is picked up on event channel 0 *\/ */
/* events_allocate(0, */
/* EVENTS_EDGE_DETECT_NONE, */
/* EVENTS_PATH_ASYNCHRONOUS, */
/* 0x29, /\* TC4 MC0 *\/ */
/* 0); */
/* /\* This event is picked up on event channel 1 *\/ */
/* events_allocate(1, */
/* EVENTS_EDGE_DETECT_NONE, */
/* EVENTS_PATH_ASYNCHRONOUS, */
/* 0x29, /\* TC4 MC0 *\/ */
/* 0); */
/* tc_enable(TC4); /\* Retrigger event means counter doesn't start yet *\/ */
/* tc_start_counter(TC4); /\* We start it manually now *\/ */
/* } */
/* void osc8m_event_source_disable(void) { */
/* tc_disable(TC4); */
/* } */
/**
* Configure the timepulse extint to generate events
*/
void timepulse_extint_event_source(void) {
/* Nothing to do: event should be already in place */
}
void timepulse_extint_event_source_disable(void) {
/* Nothing to do here */
}
/**
* Triggers a measurements the number of cycles on XOSC
*
* A callback from the timer interrupt is available. Obviously don't dwell here too long.
*/
void measure_xosc(enum xosc_measurement_t measurement_t,
measurement_result_t callback) {
measure_state = MEASURE_WAIT_FOR_FIRST_EVENT;
_measurement_t = measurement_t;
_callback = callback;
/* Timer 2 runs on GLCK1: XOSC */
bool t2_capture_channel_enables[] = {true, true};
uint32_t t2_compare_channel_values[] = {0x0000, 0x0000};
tc_init(TC2,
GCLK_GENERATOR_1,
TC_COUNTER_SIZE_32BIT,
TC_CLOCK_PRESCALER_DIV1,
TC_WAVE_GENERATION_NORMAL_FREQ,
TC_RELOAD_ACTION_GCLK,
TC_COUNT_DIRECTION_UP,
TC_WAVEFORM_INVERT_OUTPUT_NONE,
false, /* Oneshot */
false, /* Run in standby */
0x0000, /* Initial value */
0xFFFFFFFF, /* Top value */
t2_capture_channel_enables, /* Capture Channel Enables */
t2_compare_channel_values); /* Compare Channels Values */
/* Timer 2 event input captures period in CC0, pulse width in CC1 */
struct tc_events events;
events.generate_event_on_compare_channel[0] = false;
events.generate_event_on_compare_channel[1] = false;
events.generate_event_on_overflow = false;
events.invert_event_input = false;
events.on_event_perform_action = true;
events.event_action = TC_EVENT_ACTION_PPW;
tc_enable_events(TC2, &events);
/* Enable Interrupt */
TC2->COUNT32.INTENSET.reg = (1 << 4); // MC0
irq_register_handler(TC2_IRQn, TC2_INT_PRIO); /* Lowish Priority */
/* Timer 2 is event user on channel 0 */
events_attach_user(0, 2);
/* Configure an event source */
switch (measurement_t) {
case XOSC_MEASURE_OSC8M:
// osc8m_event_source(); // osc8m issues events
break;
case XOSC_MEASURE_TIMEPULSE:
timepulse_extint_event_source(); // timepulse issues events
break;
}
tc_enable(TC2);
}
void measure_xosc_disable(enum xosc_measurement_t measurement_t) {
tc_disable(TC2);
switch (measurement_t) {
case XOSC_MEASURE_OSC8M:
// osc8m_event_source_disable();
break;
case XOSC_MEASURE_TIMEPULSE:
timepulse_extint_event_source_disable();
break;
}
}
/**
* Triggered on timer 2 capture
*/
void TC2_Handler(void) {
uint32_t capture_value;
uint32_t source_freq;
awake_do_watchdog();
if (tc_get_status(TC2) & TC_STATUS_CHANNEL_0_MATCH) {
tc_clear_status(TC2, TC_STATUS_CHANNEL_0_MATCH);
switch (measure_state) {
case MEASURE_WAIT_FOR_FIRST_EVENT:
measure_state = MEASURE_MEASUREMENT; /* Start measurement */
break;
case MEASURE_MEASUREMENT:
/* Measurement done. Read off data */
capture_value = tc_get_capture_value(TC2, 0);
/* Calcuate the frequency of XOSC relative to this source */
switch (_measurement_t) {
case XOSC_MEASURE_OSC8M:
source_freq = capture_value * XOSC_GCLK1_DIVIDE;
break;
case XOSC_MEASURE_TIMEPULSE:
source_freq = capture_value * XOSC_GCLK1_DIVIDE * GPS_TIMEPULSE_FREQ * 2;
break;
}
/* Callback if we have one */
if (_callback) {
_callback(source_freq);
}
/* Disable measurement system */
measure_xosc_disable(_measurement_t);
}
}
}
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