Using this Espressif sample the default ESP32 USB serial port UART events can be used. No polling!
Source:
https://github.com/espressif/esp-idf/bl ... ple_main.c
Sending a random 43 character text over USB to a Wemos Lolin32 Lite created this USB response:
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[0;32mI (944733) myUart: uart[0] event:[0m
[0;32mI (944733) myUart: [UART DATA]: 43[0m
[0;32mI (944733) myUart: [DATA EVT]:[0m
The Quick Brown Fox Jumps Over the Lazy DogI wraped the sample in a class to get the code out of the way
To test include uartdemo.h and call myUart.init()
uartdemo.h:
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#pragma once
/* UART Events Example
This example code is in the Public Domain (or CC0 licensed, at your option.)
Unless required by applicable law or agreed to in writing, this
software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "driver/uart.h"
#include "esp_log.h"
#define EX_UART_NUM UART_NUM_0
#define PATTERN_CHR_NUM (3) /*!< Set the number of consecutive and identical characters received by receiver which defines a UART pattern*/
#define BUF_SIZE (1024)
#define RD_BUF_SIZE (BUF_SIZE)
class uartdemo
{
public:
uartdemo();
~uartdemo();
private:
static constexpr char const *TAG = "myUart";
static void uart_event_task(void *pvParameters);
public:
void init();
};
extern uartdemo myUart;uartdemo.cpp
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/**
* This example shows how to use the UART driver to handle special UART events.
*
* It also reads data from UART0 directly, and echoes it to console.
*
* - Port: UART0
* - Receive (Rx) buffer: on
* - Transmit (Tx) buffer: off
* - Flow control: off
* - Event queue: on
* - Pin assignment: TxD (default), RxD (default)
*/
#include "uartdemo.h"
static QueueHandle_t uart0_queue;
uartdemo myUart = uartdemo();
uartdemo::uartdemo()
{
}
uartdemo::~uartdemo()
{
}
void uartdemo::uart_event_task(void *pvParameters)
{
uart_event_t event;
size_t buffered_size;
uint8_t* dtmp = (uint8_t*) malloc(RD_BUF_SIZE);
for(;;) {
//Waiting for UART event.
if(xQueueReceive(uart0_queue, (void * )&event, (portTickType)portMAX_DELAY)) {
bzero(dtmp, RD_BUF_SIZE);
ESP_LOGI(TAG, "uart[%d] event:", EX_UART_NUM);
switch(event.type) {
//Event of UART receving data
/*We'd better handler data event fast, there would be much more data events than
other types of events. If we take too much time on data event, the queue might
be full.*/
case UART_DATA:
ESP_LOGI(TAG, "[UART DATA]: %d", event.size);
uart_read_bytes(EX_UART_NUM, dtmp, event.size, portMAX_DELAY);
ESP_LOGI(TAG, "[DATA EVT]:");
uart_write_bytes(EX_UART_NUM, (const char*) dtmp, event.size);
break;
//Event of HW FIFO overflow detected
case UART_FIFO_OVF:
ESP_LOGI(TAG, "hw fifo overflow");
// If fifo overflow happened, you should consider adding flow control for your application.
// The ISR has already reset the rx FIFO,
// As an example, we directly flush the rx buffer here in order to read more data.
uart_flush(EX_UART_NUM);
xQueueReset(uart0_queue);
break;
//Event of UART ring buffer full
case UART_BUFFER_FULL:
ESP_LOGI(TAG, "ring buffer full");
// If buffer full happened, you should consider encreasing your buffer size
// As an example, we directly flush the rx buffer here in order to read more data.
uart_flush(EX_UART_NUM);
xQueueReset(uart0_queue);
break;
//Event of UART RX break detected
case UART_BREAK:
ESP_LOGI(TAG, "uart rx break");
break;
//Event of UART parity check error
case UART_PARITY_ERR:
ESP_LOGI(TAG, "uart parity error");
break;
//Event of UART frame error
case UART_FRAME_ERR:
ESP_LOGI(TAG, "uart frame error");
break;
//UART_PATTERN_DET
case UART_PATTERN_DET:
ESP_LOGI(TAG, "UART PATTERN DETECTED\n");
break;
//Others
default:
ESP_LOGI(TAG, "uart event type: %d", event.type);
break;
}
}
}
free(dtmp);
dtmp = NULL;
vTaskDelete(NULL);
}
void uartdemo::init()
{
esp_log_level_set(TAG, ESP_LOG_INFO);
/* Configure parameters of an UART driver,
* communication pins and install the driver */
uart_config_t uart_config = {
.baud_rate = 115200,
.data_bits = UART_DATA_8_BITS,
.parity = UART_PARITY_DISABLE,
.stop_bits = UART_STOP_BITS_1,
.flow_ctrl = UART_HW_FLOWCTRL_DISABLE
};
uart_param_config(EX_UART_NUM, &uart_config);
//Set UART log level
esp_log_level_set(TAG, ESP_LOG_INFO);
//Set UART pins (using UART0 default pins ie no changes.)
uart_set_pin(EX_UART_NUM, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
//Install UART driver, and get the queue.
//uart0_queue = xQueueCreate(5, sizeof(uint8_t)); //initialize the queue
uart_driver_install(EX_UART_NUM, BUF_SIZE * 2, BUF_SIZE * 2, 20, &uart0_queue, 0);
//Set uart pattern detect function.
uart_enable_pattern_det_intr(EX_UART_NUM, '+', PATTERN_CHR_NUM, 10000, 10, 10);
//Reset the pattern queue length to record at most 20 pattern positions.
//uart_pattern_queue_reset(EX_UART_NUM, 20);
//Create a task to handler UART event from ISR
xTaskCreate(uart_event_task, "uart_event_task", 2048, NULL, 12, NULL);
}
Avoiding intensive polling may save some CPU power?
