// 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/rmt_struct.h"
#include "soc/pcnt_struct.h"
#include "soc/pcnt_reg.h"
#include "soc/gpio_sig_map.h"
#include "soc/dport_reg.h"
#include "rom/gpio.h"
#include "rom/ets_sys.h"
#include "driver/gpio.h"
#include "esp_intr_alloc.h"
#include "freertos/FreeRTOS.h"
#include "driver/periph_ctrl.h"
/* Select which RMT and PCNT channels, and GPIO to use */
#define REF_CLOCK_RMT_CHANNEL 7
#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;
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.apb_conf.fifo_mask = 1;
rmt_item32_t data = {
.duration0 = 1,
.level0 = 1,
.duration1 = 0,
.level1 = 0
};
RMTMEM.chan[REF_CLOCK_RMT_CHANNEL].data32[0] = data;
RMTMEM.chan[REF_CLOCK_RMT_CHANNEL].data32[1].val = 0;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf0.clk_en = 1;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf1.tx_start = 0;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf1.mem_owner = 0;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf1.mem_rd_rst = 1;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf1.apb_mem_rst = 1;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf0.carrier_en = 0;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf0.div_cnt = 1;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf0.mem_size = 1;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf1.ref_always_on = 0;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf1.tx_conti_mode = 1;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf1.tx_start = 1;
// Route signal to PCNT
int pcnt_sig_idx = (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);
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.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.ch0_hctrl_mode = 0;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.ch0_lctrl_mode = 0;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.ch0_pos_mode = 1;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.ch0_neg_mode = 1;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.thr_l_lim_en = 0;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.thr_h_lim_en = 1;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.thr_zero_en = 0;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.thr_thres0_en = 0;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf0.thr_thres1_en = 0;
PCNT.conf_unit[REF_CLOCK_PCNT_UNIT].conf2.cnt_h_lim = REF_CLOCK_PRESCALER_MS * 1000;
// Enable PCNT and wait for it to start counting
PCNT.ctrl.val &= ~(BIT(REF_CLOCK_PCNT_UNIT * 2 + 1));
PCNT.ctrl.val |= BIT(REF_CLOCK_PCNT_UNIT * 2);
PCNT.ctrl.val &= ~BIT(REF_CLOCK_PCNT_UNIT * 2);
// 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.int_clr.val = BIT(REF_CLOCK_PCNT_UNIT);
PCNT.int_ena.val = BIT(REF_CLOCK_PCNT_UNIT);
}
static void IRAM_ATTR pcnt_isr(void* arg)
{
portENTER_CRITICAL(&s_lock);
PCNT.int_clr.val = BIT(REF_CLOCK_PCNT_UNIT);
s_milliseconds += REF_CLOCK_PRESCALER_MS;
portEXIT_CRITICAL(&s_lock);
}
void ref_clock_deinit()
{
assert(s_intr_handle && "deinit called without init");
// Disable interrupt
PCNT.int_ena.val &= ~BIT(REF_CLOCK_PCNT_UNIT);
esp_intr_free(s_intr_handle);
s_intr_handle = NULL;
// Disable RMT
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf1.tx_start = 0;
RMT.conf_ch[REF_CLOCK_RMT_CHANNEL].conf0.clk_en = 0;
periph_module_disable(PERIPH_RMT_MODULE);
// Disable PCNT
PCNT.ctrl.val |= ~(BIT(REF_CLOCK_PCNT_UNIT * 2 + 1));
periph_module_disable(PERIPH_PCNT_MODULE);
}
uint64_t ref_clock_get()
{
portENTER_CRITICAL(&s_lock);
uint32_t microseconds = PCNT.cnt_unit[REF_CLOCK_PCNT_UNIT].cnt_val;
uint32_t milliseconds = s_milliseconds;
if (PCNT.int_st.val & BIT(REF_CLOCK_PCNT_UNIT)) {
// refresh counter value, in case the overflow has happened after reading cnt_val
microseconds = PCNT.cnt_unit[REF_CLOCK_PCNT_UNIT].cnt_val;
milliseconds += REF_CLOCK_PRESCALER_MS;
}
portEXIT_CRITICAL(&s_lock);
return 1000 * (uint64_t) milliseconds + (uint64_t) microseconds;
}