kopia lustrzana https://github.com/espressif/esp-idf
175 wiersze
7.3 KiB
C
175 wiersze
7.3 KiB
C
// Copyright 2017-2020 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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* Some unit test cases need to have access to reliable timestamps even when CPU and APB clock frequencies change over time.
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* This reference clock is built upon two peripherals: one RMT channel and one PCNT channel (hopefully we can have these two peripherals in all ESP chips).
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*
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* +---------------------+ 500KHz Square Wave +--------------------------+
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* | RMT (channel 0, TX) +----------------------------------->+ PCNT (unit 0, channel 0) |
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* +---------------------+ +--------------------------+
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*
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* RMT TX channel is configured to use a fixed clock (e.g. REF_TICK, XTAL) as clock source, so that our ref clock won't be affected during APB/CPU clock switch.
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* Configure RMT channel to generate a 500KHz square wave (using carrier feature) to one GPIO.
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* PCNT takes the input signal from the GPIO and counts the edges (which occur at 1MHz frequency).
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* PCNT counter is only 16 bit wide, an interrupt is configured to trigger when the counter reaches 30000,
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* incrementing a 32-bit millisecond counter maintained by software.
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*/
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#include "sdkconfig.h"
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#include "test_utils.h"
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#include "freertos/FreeRTOS.h"
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#include "esp_intr_alloc.h"
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#include "driver/periph_ctrl.h"
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#include "soc/gpio_sig_map.h"
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#include "soc/gpio_periph.h"
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#include "hal/rmt_hal.h"
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#include "hal/rmt_ll.h"
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#include "hal/pcnt_hal.h"
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#include "esp_rom_gpio.h"
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#include "esp_rom_sys.h"
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#define REF_CLOCK_RMT_CHANNEL 0 // RMT channel 0
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#define REF_CLOCK_PCNT_UNIT 0 // PCNT unit 0 channel 0
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#define REF_CLOCK_GPIO 21 // GPIO used to combine RMT out signal with PCNT input signal
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#define REF_CLOCK_PRESCALER_MS 30 // PCNT high threshold interrupt fired every 30ms
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static void IRAM_ATTR pcnt_isr(void *arg);
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static intr_handle_t s_intr_handle;
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static portMUX_TYPE s_lock = portMUX_INITIALIZER_UNLOCKED;
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static volatile uint32_t s_milliseconds;
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static rmt_hal_context_t s_rmt_hal;
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static pcnt_hal_context_t s_pcnt_hal;
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void ref_clock_init(void)
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{
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assert(s_intr_handle == NULL && "ref clock already initialized");
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// Route RMT output to GPIO matrix
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esp_rom_gpio_connect_out_signal(REF_CLOCK_GPIO, RMT_SIG_OUT0_IDX, false, false);
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// Initialize RMT
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periph_module_enable(PERIPH_RMT_MODULE);
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rmt_hal_init(&s_rmt_hal);
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rmt_item32_t data = {
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.duration0 = 1,
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.level0 = 1,
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.duration1 = 0,
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.level1 = 0
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};
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rmt_ll_enable_drive_clock(s_rmt_hal.regs, true);
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#if CONFIG_IDF_TARGET_ESP32 || CONFIG_IDF_TARGET_ESP32S2
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rmt_ll_set_counter_clock_src(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, 0); // select REF_TICK (1MHz)
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#else
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rmt_ll_set_sclk(s_rmt_hal.regs, 3, 39, 0, 0); // XTAL(40MHz), rmt_sclk => 1MHz (40/(1+39))
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#endif
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rmt_hal_set_counter_clock(&s_rmt_hal, REF_CLOCK_RMT_CHANNEL, 1000000, 1000000); // counter clock: 1MHz
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rmt_ll_enable_tx_idle(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, true); // enable idle output
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rmt_ll_set_tx_idle_level(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, 1); // idle level: 1
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rmt_ll_enable_carrier(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, true);
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#if !CONFIG_IDF_TARGET_ESP32
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rmt_ll_tx_set_carrier_always_on(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, true);
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#endif
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rmt_hal_set_carrier_clock(&s_rmt_hal, REF_CLOCK_RMT_CHANNEL, 1000000, 500000, 0.5); // set carrier to 500KHz
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rmt_ll_set_carrier_on_level(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, 1);
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rmt_ll_enable_mem_access(s_rmt_hal.regs, true);
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rmt_ll_reset_tx_pointer(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL);
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rmt_ll_set_mem_blocks(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, 1);
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rmt_ll_write_memory(s_rmt_hal.mem, REF_CLOCK_RMT_CHANNEL, &data, 1, 0);
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rmt_ll_enable_tx_loop(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, false);
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rmt_ll_start_tx(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL);
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// Route signal to PCNT
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esp_rom_gpio_connect_in_signal(REF_CLOCK_GPIO, PCNT_SIG_CH0_IN0_IDX, false);
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if (REF_CLOCK_GPIO != 20) {
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PIN_INPUT_ENABLE(GPIO_PIN_MUX_REG[REF_CLOCK_GPIO]);
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} else {
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PIN_INPUT_ENABLE(PERIPHS_IO_MUX_GPIO20_U);
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}
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// Initialize PCNT
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periph_module_enable(PERIPH_PCNT_MODULE);
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pcnt_hal_init(&s_pcnt_hal, REF_CLOCK_PCNT_UNIT);
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pcnt_ll_set_mode(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, PCNT_CHANNEL_0,
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PCNT_COUNT_INC, PCNT_COUNT_INC,
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PCNT_MODE_KEEP, PCNT_MODE_KEEP);
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pcnt_ll_event_disable(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_L_LIM);
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pcnt_ll_event_enable(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_H_LIM);
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pcnt_ll_event_disable(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_ZERO);
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pcnt_ll_event_disable(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_THRES_0);
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pcnt_ll_event_disable(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_THRES_1);
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pcnt_ll_set_event_value(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, PCNT_EVT_H_LIM, REF_CLOCK_PRESCALER_MS * 1000);
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// Enable PCNT and wait for it to start counting
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pcnt_ll_counter_resume(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT);
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pcnt_ll_counter_clear(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT);
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esp_rom_delay_us(10000);
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// Enable interrupt
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s_milliseconds = 0;
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ESP_ERROR_CHECK(esp_intr_alloc(ETS_PCNT_INTR_SOURCE, ESP_INTR_FLAG_IRAM, pcnt_isr, NULL, &s_intr_handle));
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pcnt_ll_clear_intr_status(s_pcnt_hal.dev, BIT(REF_CLOCK_PCNT_UNIT));
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pcnt_ll_intr_enable(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT);
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}
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static void IRAM_ATTR pcnt_isr(void *arg)
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{
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portENTER_CRITICAL_ISR(&s_lock);
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pcnt_ll_clear_intr_status(s_pcnt_hal.dev, BIT(REF_CLOCK_PCNT_UNIT));
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s_milliseconds += REF_CLOCK_PRESCALER_MS;
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portEXIT_CRITICAL_ISR(&s_lock);
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}
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void ref_clock_deinit()
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{
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assert(s_intr_handle && "ref clock deinit called without init");
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// Disable interrupt
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pcnt_ll_intr_disable(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT);
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esp_intr_free(s_intr_handle);
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s_intr_handle = NULL;
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// Disable RMT
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rmt_ll_enable_carrier(s_rmt_hal.regs, REF_CLOCK_RMT_CHANNEL, false);
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periph_module_disable(PERIPH_RMT_MODULE);
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// Disable PCNT
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pcnt_ll_counter_pause(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT);
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periph_module_disable(PERIPH_PCNT_MODULE);
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}
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uint64_t ref_clock_get()
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{
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portENTER_CRITICAL(&s_lock);
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int16_t microseconds = 0;
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pcnt_ll_get_counter_value(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, µseconds);
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uint32_t milliseconds = s_milliseconds;
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uint32_t intr_status = 0;
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pcnt_ll_get_intr_status(s_pcnt_hal.dev, &intr_status);
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if (intr_status & BIT(REF_CLOCK_PCNT_UNIT)) {
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// refresh counter value, in case the overflow has happened after reading cnt_val
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pcnt_ll_get_counter_value(s_pcnt_hal.dev, REF_CLOCK_PCNT_UNIT, µseconds);
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milliseconds += REF_CLOCK_PRESCALER_MS;
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}
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portEXIT_CRITICAL(&s_lock);
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return 1000 * (uint64_t)milliseconds + (uint64_t)microseconds;
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}
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