tsoftuart: add a softare timer base UART driver, and example.

examples/tsoftuart/.gitignore

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+!local.mk

examples/tsoftuart/FreeRTOSConfig.h

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+#define configUSE_TRACE_FACILITY 1
+#define configGENERATE_RUN_TIME_STATS 1
+#define portGET_RUN_TIME_COUNTER_VALUE() (RTC.COUNTER)
+#define portCONFIGURE_TIMER_FOR_RUN_TIME_STATS() {}
+
+/* Use the defaults for everything else */
+#include_next<FreeRTOSConfig.h>

examples/tsoftuart/Makefile

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+# Makefile for tsfotuart example
+PROGRAM=tsoftuart
+EXTRA_COMPONENTS=extras/dhcpserver extras/wificfg extras/mactimer extras/tsoftuart
+
+# For the mDNS responder included with lwip:
+EXTRA_CFLAGS += -DLWIP_MDNS_RESPONDER=1 -DLWIP_NUM_NETIF_CLIENT_DATA=1 -DLWIP_NETIF_EXT_STATUS_CALLBACK=1
+
+# Avoid writing the wifi state to flash when using wificfg.
+EXTRA_CFLAGS += -DWIFI_PARAM_SAVE=0
+
+EXTRA_CFLAGS += -DWIFICFG_CLIENT_TASK=1 -DWIFICFG_IRAM_TEST=1
+
+include ../../common.mk

examples/tsoftuart/local.mk

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+FLASH_SIZE ?= 32

examples/tsoftuart/tsoftuart.c

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+/*
+ * Example timer based software UART drive.
+ *
+ * Copyright (C) 2019 OurAirQuality.org
+ *
+ * Licensed under the Apache License, Version 2.0, January 2004 (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/
+ *
+ * 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 CONTRIBUTORS 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 WITH THE SOFTWARE.
+ *
+ */
+
+#include <string.h>
+#include <ctype.h>
+
+#include <espressif/esp_common.h>
+#include <espressif/user_interface.h>
+#include <esp/uart.h>
+#include <FreeRTOS.h>
+#include <task.h>
+
+#include "lwip/sockets.h"
+
+#include "wificfg/wificfg.h"
+#include "tsoftuart/tsoftuart.h"
+
+static void tsoftuart_task(void *pvParameters)
+{
+    /* Initialize the UART Tx. */
+    uint32_t tx_pin = *(uint32_t *)pvParameters;
+    struct tsoftuart *uart = tsoftuart_init(tx_pin, 9600);
+    
+    for (;;) {
+        /* Reset the timing error records. */
+        uart->output_queue_error_low = 0;
+        uart->output_queue_error_high = 0;
+
+        char str[] = "Hello 0123456789 abcdefghijklmnopqrstuvwxyz\r\n";
+        for (size_t i = 0; i < strlen(str); i++) {
+            tsoftuart_putc(uart, str[i]);
+        }
+
+        /* Check the timing error. */
+        if (uart->output_queue_error_high > 2 || uart->output_queue_error_low < -2) {
+            tsoftuart_write(uart, "X\r\n", 3);
+        }
+
+        vTaskDelay(200 / portTICK_PERIOD_MS);
+    }
+}
+
+void user_init(void)
+{
+    uart_set_baud(0, 115200);
+    printf("SDK version:%s\n", sdk_system_get_sdk_version());
+
+    wificfg_init(80, NULL);
+
+    /* Start two tasks writing to different pins. */
+
+    static uint32_t tx_pin1 = 1;
+    xTaskCreate(&tsoftuart_task, "tsoftuart1", 256, &tx_pin1, 1, NULL);
+
+    static uint32_t tx_pin2 = 2;
+    xTaskCreate(&tsoftuart_task, "tsoftuart2", 256, &tx_pin2, 1, NULL);
+}