IRQ driven RX on UART0

core/newlib_syscalls.c

@@ -45,8 +45,9 @@ long _write_r(struct _reent *r, int fd, const char *ptr, int len )
 /* syscall implementation for stdio read from UART
 
    at the moment UART functionality is all still in the binary SDK
+   but there is support for IRQ driven UART0 RX in extras/serial-driver
  */
-long _read_r( struct _reent *r, int fd, char *ptr, int len )
+long __attribute__((weak)) _read_r( struct _reent *r, int fd, char *ptr, int len )
 {
   for(int i = 0; i < len; i++) {
     char ch;

examples/terminal/FreeRTOSConfig.h

@@ -0,0 +1,12 @@
+/* Terminal FreeRTOSConfig overrides.
+
+   This is intended as an example of overriding some of the default FreeRTOSConfig settings,
+   which are otherwise found in FreeRTOS/Source/include/FreeRTOSConfig.h
+*/
+
+/* The serial driver depends on counting semaphores */
+#define configUSE_COUNTING_SEMAPHORES 1
+
+/* Use the defaults for everything else */
+#include_next<FreeRTOSConfig.h>
+

examples/terminal/Makefile

@@ -0,0 +1,3 @@
+PROGRAM=terminal
+EXTRA_COMPONENTS=extras/serial-driver
+include ../../common.mk

examples/terminal/terminal.c

@@ -0,0 +1,37 @@
+/* Serial terminal example
+ * UART RX is interrupt driven
+ * Read characters until \n and echo back
+ *
+ * This sample code is in the public domain.
+ */
+
+#include <stdint.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <espressif/esp_common.h>
+#include <serial_driver.h>
+
+#define BUFFER_SIZE (81)
+
+void user_init(void)
+{
+    char buffer[BUFFER_SIZE];
+    uint32_t i = 0;
+    sdk_uart_div_modify(0, UART_CLK_FREQ / 115200);
+    while(1) {
+        char ch;
+        // The thread will block here until there is data available
+        // NB. read(...) may be called from user_init or from a thread
+        // We can check how many characters are available in the RX buffer
+        // with uint32_t uart0_num_char(void);
+        if (read(0, (void*)&ch, 1)) { // 0 is stdin
+            if (i == BUFFER_SIZE-2 || ch == '\n') {
+                buffer[i] = 0;
+                printf("Unknown command: %s\n", (char*) buffer);
+                i = 0;
+            } else {
+                buffer[i++] = ch;
+            }
+        }
+    }
+}

extras/serial-driver/component.mk

@@ -0,0 +1,11 @@
+# Component makefile for extras/serial-driver
+#
+# See examples/terminal for usage
+
+INC_DIRS += $(ROOT)extras/serial-driver
+
+# args for passing into compile rule generation
+extras/serial-driver_INC_DIR =  $(ROOT)extras/serial-driver
+extras/serial-driver_SRC_DIR =  $(ROOT)extras/serial-driver
+
+$(eval $(call component_compile_rules,extras/serial-driver))

extras/serial-driver/serial_driver.c

@@ -0,0 +1,119 @@
+/* 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Johan Kanflo (github.com/kanflo)
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * 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
+ * AUTHORS 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 IN
+ * THE SOFTWARE.
+ */
+
+#include <esp8266.h>
+#include <espressif/esp8266/esp8266.h>
+#include <espressif/esp8266/uart_register.h>
+#include <FreeRTOS.h>
+#include <semphr.h>
+
+#if (configUSE_COUNTING_SEMAPHORES == 0)
+ #error "You need to define configUSE_COUNTING_SEMAPHORES in a local FreeRTOSConfig.h, see examples/terminal/FreeRTOSConfig.h"
+#endif
+
+// IRQ driven UART RX driver for ESP8266 written for use with esp-open-rtos
+// TODO: Handle UART1
+
+#define UART0_RX_SIZE  (81)
+
+#ifndef UART0
+#define UART0 (0)
+#endif
+
+static xSemaphoreHandle uart0_sem = NULL;
+static char rx_buf[UART0_RX_SIZE];
+static uint8_t rd_pos = 0;
+static uint8_t wr_pos = 0;
+static bool inited = false;
+
+static void uart0_rx_init(void);
+
+
+IRAM void uart0_rx_handler(void)
+{
+    // TODO: Handle UART1, see reg 0x3ff20020, bit2, bit0 represents uart1 and uart0 respectively
+    if (UART_RXFIFO_FULL_INT_ST != (READ_PERI_REG(UART_INT_ST(UART0)) & UART_RXFIFO_FULL_INT_ST)) {
+        return;
+    }
+    WRITE_PERI_REG(UART_INT_CLR(UART0), UART_RXFIFO_FULL_INT_CLR);
+    while (READ_PERI_REG(UART_STATUS(UART0)) & (UART_RXFIFO_CNT << UART_RXFIFO_CNT_S)) {
+        char ch = READ_PERI_REG(UART_FIFO(UART0)) & 0xff;
+        uint8_t wr_next = (wr_pos+1) % UART0_RX_SIZE;
+        if (wr_next != rd_pos) {
+            rx_buf[wr_pos] = ch;
+            wr_pos = (wr_pos+1) % UART0_RX_SIZE;
+            xSemaphoreGiveFromISR(uart0_sem, NULL);
+        }
+    }
+}
+
+uint32_t uart0_num_char(void)
+{
+    uint32_t count;
+    if (!inited) uart0_rx_init();
+    _xt_isr_mask(1 << INUM_UART);
+    if (rd_pos > wr_pos) count = rd_pos - wr_pos;
+    else count = wr_pos - rd_pos;
+    _xt_isr_unmask(1 << INUM_UART);
+    return count;
+}
+
+// _read_r in core/newlib_syscalls.c will be skipped in favour of this function
+long _read_r(struct _reent *r, int fd, char *ptr, int len)
+{
+    if (!inited) uart0_rx_init();
+    for(int i = 0; i < len; i++) {
+        char ch;
+        if (xSemaphoreTake(uart0_sem, portMAX_DELAY)) {
+            _xt_isr_mask(1 << INUM_UART);
+            ch = rx_buf[rd_pos];
+            rd_pos = (rd_pos+1) % UART0_RX_SIZE;
+            _xt_isr_unmask(1 << INUM_UART);
+            ptr[i] = ch;
+        }
+    }
+    return len;
+}
+
+static void uart0_rx_init(void)
+{
+    int trig_lvl = 1;
+    uart0_sem = xSemaphoreCreateCounting(UART0_RX_SIZE, 0);
+
+    _xt_isr_attach(INUM_UART, uart0_rx_handler);
+    _xt_isr_unmask(1 << INUM_UART);
+
+    //clear rx and tx fifo,not ready
+    SET_PERI_REG_MASK(UART_CONF0(UART0), UART_RXFIFO_RST | UART_TXFIFO_RST);
+    CLEAR_PERI_REG_MASK(UART_CONF0(UART0), UART_RXFIFO_RST | UART_TXFIFO_RST);
+
+    //set rx fifo trigger
+    WRITE_PERI_REG(UART_CONF1(UART0), (trig_lvl & UART_RXFIFO_FULL_THRHD) << UART_RXFIFO_FULL_THRHD_S);
+
+    //clear all interrupt
+    WRITE_PERI_REG(UART_INT_CLR(UART0), 0xffff);
+    //enable rx_interrupt
+    SET_PERI_REG_MASK(UART_INT_ENA(UART0), UART_RXFIFO_FULL_INT_ENA);    
+    inited = true;
+}

extras/serial-driver/serial_driver.h

@@ -0,0 +1,33 @@
+/* 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Johan Kanflo (github.com/kanflo)
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * 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
+ * AUTHORS 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 IN
+ * THE SOFTWARE.
+ */
+
+#ifndef __I2C_H__
+#define __I2C_H__
+#endif
+
+#include <stdint.h>
+#include <stdbool.h>
+
+// Return number of characters waiting in UART0
+uint32_t uart0_num_char(void);