esp-idf/tools/unit-test-app/components/test_utils/ref_clock.c

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// Copyright 2017 Espressif Systems (Shanghai) PTE LTD
//
// 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.
/* Unit tests need to have access to reliable timestamps even if CPU and APB
* clock frequencies change over time. This reference clock is built upon two
* peripherals: one RMT channel and one PCNT channel, plus one GPIO to connect
* these peripherals.
*
* RMT channel is configured to use REF_TICK as clock source, which is a 1 MHz
* clock derived from APB_CLK using a set of dividers. The divider is changed
* automatically by hardware depending on the current clock source of APB_CLK.
* For example, if APB_CLK is derived from PLL, one divider is used, and when
* APB_CLK is derived from XTAL, another divider is used. RMT channel clocked
* by REF_TICK is configured to generate a continuous 0.5 MHz signal, which is
* connected to a GPIO. PCNT takes the input signal from this GPIO and counts
* the edges (which occur at 1MHz frequency). PCNT counter is only 16 bit wide,
* so an interrupt is configured to trigger when the counter reaches 30000,
* incrementing a 32-bit millisecond counter maintained by software.
* Together these two counters may be used at any time to obtain the timestamp.
*/
#include "test_utils.h"
#include "soc/soc.h"
#include "hal/rmt_hal.h"
#include "hal/rmt_ll.h"
#include "soc/pcnt_caps.h"
#include "hal/pcnt_hal.h"
#include "soc/gpio_periph.h"
#include "soc/dport_reg.h"
#include "esp_intr_alloc.h"
#include "freertos/FreeRTOS.h"
#include "driver/periph_ctrl.h"
#if CONFIG_IDF_TARGET_ESP32
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#include "esp32/rom/gpio.h"
#elif CONFIG_IDF_TARGET_ESP32S2
#include "esp32s2/rom/gpio.h"
#endif
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#include "sdkconfig.h"
/* Select which RMT and PCNT channels, and GPIO to use */
#define REF_CLOCK_RMT_CHANNEL RMT_CHANNELS_NUM - 1
#define REF_CLOCK_PCNT_UNIT 0
#define REF_CLOCK_GPIO 21
#define REF_CLOCK_PRESCALER_MS 30
static void IRAM_ATTR pcnt_isr(void* arg);
static intr_handle_t s_intr_handle;
static portMUX_TYPE s_lock = portMUX_INITIALIZER_UNLOCKED;
static volatile uint32_t s_milliseconds;
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static int get_pcnt_sig(void)
{
#if CONFIG_IDF_TARGET_ESP32
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return (REF_CLOCK_PCNT_UNIT < 5) ?
PCNT_SIG_CH0_IN0_IDX + 4 * REF_CLOCK_PCNT_UNIT :
PCNT_SIG_CH0_IN5_IDX + 4 * (REF_CLOCK_PCNT_UNIT - 5);
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#elif CONFIG_IDF_TARGET_ESP32S2
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return PCNT_SIG_CH0_IN0_IDX + 4 * REF_CLOCK_PCNT_UNIT;
#endif
}
static rmt_hal_context_t s_rmt;
static pcnt_hal_context_t s_pcnt;
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void ref_clock_init()
{
assert(s_intr_handle == NULL && "already initialized");
// Route RMT output to GPIO matrix
gpio_matrix_out(REF_CLOCK_GPIO, RMT_SIG_OUT0_IDX + REF_CLOCK_RMT_CHANNEL, false, false);
// Initialize RMT
periph_module_enable(PERIPH_RMT_MODULE);
rmt_hal_init(&s_rmt);
rmt_ll_enable_mem_access(s_rmt.regs, true);
rmt_item32_t data = {
.duration0 = 1,
.level0 = 1,
.duration1 = 0,
.level1 = 0
};
rmt_hal_transmit(&s_rmt, REF_CLOCK_RMT_CHANNEL, &data, 1, 0);
rmt_ll_start_tx(s_rmt.regs, REF_CLOCK_RMT_CHANNEL);
rmt_ll_set_mem_owner(s_rmt.regs, REF_CLOCK_RMT_CHANNEL, 0);
rmt_ll_reset_tx_pointer(s_rmt.regs, REF_CLOCK_RMT_CHANNEL);
rmt_ll_enable_carrier(s_rmt.regs, REF_CLOCK_RMT_CHANNEL, false);
rmt_ll_set_counter_clock_div(s_rmt.regs, REF_CLOCK_RMT_CHANNEL, 1);
rmt_ll_set_mem_blocks(s_rmt.regs, REF_CLOCK_RMT_CHANNEL, 1);
rmt_ll_set_counter_clock_src(s_rmt.regs, REF_CLOCK_RMT_CHANNEL, 0);
rmt_ll_enable_tx_cyclic(s_rmt.regs, REF_CLOCK_RMT_CHANNEL, true);
rmt_ll_start_tx(s_rmt.regs, REF_CLOCK_RMT_CHANNEL);
// Route signal to PCNT
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int pcnt_sig_idx = get_pcnt_sig();
gpio_matrix_in(REF_CLOCK_GPIO, pcnt_sig_idx, false);
if (REF_CLOCK_GPIO != 20) {
PIN_INPUT_ENABLE(GPIO_PIN_MUX_REG[REF_CLOCK_GPIO]);
} else {
PIN_INPUT_ENABLE(PERIPHS_IO_MUX_GPIO20_U);
}
// Initialize PCNT
periph_module_enable(PERIPH_PCNT_MODULE);
pcnt_hal_init(&s_pcnt, REF_CLOCK_PCNT_UNIT);
pcnt_ll_set_mode(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, PCNT_CHANNEL_0,
PCNT_COUNT_INC, PCNT_COUNT_INC,
PCNT_MODE_KEEP, PCNT_MODE_KEEP);
pcnt_ll_event_disable(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_L_LIM);
pcnt_ll_event_enable(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_H_LIM);
pcnt_ll_event_disable(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_ZERO);
pcnt_ll_event_disable(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_THRES_0);
pcnt_ll_event_disable(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_THRES_1);
pcnt_ll_set_event_value(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_H_LIM, REF_CLOCK_PRESCALER_MS * 1000);
// Enable PCNT and wait for it to start counting
pcnt_ll_counter_resume(s_pcnt.dev, REF_CLOCK_PCNT_UNIT);
pcnt_ll_counter_clear(s_pcnt.dev, REF_CLOCK_PCNT_UNIT);
ets_delay_us(10000);
// Enable interrupt
s_milliseconds = 0;
ESP_ERROR_CHECK(esp_intr_alloc(ETS_PCNT_INTR_SOURCE, ESP_INTR_FLAG_IRAM, pcnt_isr, NULL, &s_intr_handle));
pcnt_ll_clear_intr_status(s_pcnt.dev, BIT(REF_CLOCK_PCNT_UNIT));
pcnt_ll_intr_enable(s_pcnt.dev, REF_CLOCK_PCNT_UNIT);
}
static void IRAM_ATTR pcnt_isr(void* arg)
{
portENTER_CRITICAL_ISR(&s_lock);
pcnt_ll_clear_intr_status(s_pcnt.dev, BIT(REF_CLOCK_PCNT_UNIT));
s_milliseconds += REF_CLOCK_PRESCALER_MS;
portEXIT_CRITICAL_ISR(&s_lock);
}
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void ref_clock_deinit()
{
assert(s_intr_handle && "deinit called without init");
// Disable interrupt
pcnt_ll_intr_disable(s_pcnt.dev, REF_CLOCK_PCNT_UNIT);
esp_intr_free(s_intr_handle);
s_intr_handle = NULL;
// Disable RMT
rmt_ll_stop_tx(s_rmt.regs, REF_CLOCK_RMT_CHANNEL);
periph_module_disable(PERIPH_RMT_MODULE);
// Disable PCNT
pcnt_ll_counter_pause(s_pcnt.dev, REF_CLOCK_PCNT_UNIT);
periph_module_disable(PERIPH_PCNT_MODULE);
}
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uint64_t ref_clock_get()
{
portENTER_CRITICAL(&s_lock);
int16_t microseconds = 0;
pcnt_ll_get_counter_value(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, &microseconds);
uint32_t milliseconds = s_milliseconds;
uint32_t intr_status = 0;
pcnt_ll_get_intr_status(s_pcnt.dev, &intr_status);
if (intr_status & BIT(REF_CLOCK_PCNT_UNIT)) {
// refresh counter value, in case the overflow has happened after reading cnt_val
pcnt_ll_get_counter_value(s_pcnt.dev, REF_CLOCK_PCNT_UNIT, &microseconds);
milliseconds += REF_CLOCK_PRESCALER_MS;
}
portEXIT_CRITICAL(&s_lock);
return 1000 * (uint64_t) milliseconds + (uint64_t) microseconds;
}