Interrupt driven stdin UART driver

core/newlib_syscalls.c

@@ -52,7 +52,7 @@ long _write_r(struct _reent *r, int fd, const char *ptr, int len )
 }
 
 /* syscall implementation for stdio read from UART */
-long _read_r( struct _reent *r, int fd, char *ptr, int len )
+__attribute__ ((weak)) long _read_r( struct _reent *r, int fd, char *ptr, int len )
 {
     int ch, i;
 

examples/terminal/Makefile

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

examples/terminal/terminal.c

@@ -1,6 +1,6 @@
 /* Serial terminal example
  * UART RX is interrupt driven
- * Read characters until \n and echo back
+ * Implements a simple GPIO terminal for setting and clearing GPIOs
  *
  * This sample code is in the public domain.
  */
@@ -8,30 +8,110 @@
 #include <stdint.h>
 #include <sys/types.h>
 #include <unistd.h>
-#include <espressif/esp_common.h>
+#include <string.h>
-#include <serial_driver.h>
+#include <esp8266.h>
+#include <esp/uart.h>
+#include "FreeRTOS.h"
+#include "task.h"
 
+#define MAX_ARGC (10)
 #define BUFFER_SIZE (81)
 
-void user_init(void)
+static void cmd_on(uint32_t argc, char *argv[])
 {
-    char buffer[BUFFER_SIZE];
+    if (argc >= 2) {
-    uint32_t i = 0;
+        for(int i=1; i<argc; i++) {
-    sdk_uart_div_modify(0, UART_CLK_FREQ / 115200);
+            uint8_t gpio_num = atoi(argv[i]);
+            gpio_enable(gpio_num, GPIO_OUTPUT);
+            gpio_write(gpio_num, true);
+            printf("On %d\n", gpio_num);
+        }
+    } else {
+        printf("Error: missing gpio number.\n");
+    }
+}
+
+static void cmd_off(uint32_t argc, char *argv[])
+{
+    if (argc >= 2) {
+        for(int i=1; i<argc; i++) {
+            uint8_t gpio_num = atoi(argv[i]);
+            gpio_enable(gpio_num, GPIO_OUTPUT);
+            gpio_write(gpio_num, false);
+            printf("Off %d\n", gpio_num);
+        }
+    } else {
+        printf("Error: missing gpio number.\n");
+    }
+}
+
+static void cmd_help(uint32_t argc, char *argv[])
+{
+    printf("on <gpio number> [ <gpio number>]+     Set gpio to 1\n");
+    printf("off <gpio number> [ <gpio number>]+    Set gpio to 0\n");
+    printf("sleep                                  Take a nap\n");
+    printf("\nExample:\n");
+    printf("  on 0<enter> switches on gpio 0\n");
+    printf("  on 0 2 4<enter> switches on gpios 0, 2 and 4\n");
+}
+
+static void cmd_sleep(uint32_t argc, char *argv[])
+{
+    printf("Type away while I take a 2 second nap (ie. let you test the UART HW FIFO\n");
+    vTaskDelay(2000 / portTICK_RATE_MS);
+}
+
+static void handle_command(char *cmd)
+{
+    char *argv[MAX_ARGC];
+    int argc = 1;
+    char *temp, *rover;
+    memset((void*) argv, 0, sizeof(argv));
+    argv[0] = cmd;
+    rover = cmd;
+    // Split string "<command> <argument 1> <argument 2>  ...  <argument N>"
+    // into argv, argc style
+    while(argc < MAX_ARGC && (temp = strstr(rover, " "))) {
+        rover = &(temp[1]);
+        argv[argc++] = rover;
+        *temp = 0;
+    }
+
+    if (strlen(argv[0]) > 0) {
+        if (strcmp(argv[0], "help") == 0) cmd_help(argc, argv);
+        else if (strcmp(argv[0], "on") == 0) cmd_on(argc, argv);
+        else if (strcmp(argv[0], "off") == 0) cmd_off(argc, argv);
+        else if (strcmp(argv[0], "sleep") == 0) cmd_sleep(argc, argv);
+        else printf("Unknown command %s, try 'help'\n", argv[0]);
+    }
+}
+
+static void gpiomon()
+{
+    char ch;
+    char cmd[81];
+    int i = 0;
+    printf("\n\n\nWelcome to gpiomon. Type 'help<enter>' for, well, help\n");
+    printf("%% ");
     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') {
+            printf("%c", ch);
-                buffer[i] = 0;
+            if (ch == '\n' || ch == '\r') {
-                printf("Unknown command: %s\n", (char*) buffer);
+                cmd[i] = 0;
                 i = 0;
+                printf("\n");
+                handle_command((char*) cmd);
+                printf("%% ");
             } else {
-                buffer[i++] = ch;
+                if (i < sizeof(cmd)) cmd[i++] = ch;
             }
         }
     }
 }
+
+void user_init(void)
+{
+    uart_set_baud(0, 115200);
+    setbuf(stdout, NULL);
+    gpiomon();
+}

extras/serial-driver/component.mk

@@ -1,11 +0,0 @@
-# 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/stdin_uart_interrupt/README.txt

@@ -0,0 +1,11 @@
+This module adds interrupt driven receive on UART 0. Using semaphores, a thread
+calling read(...) when no data is available will block in an RTOS expected
+manner until data arrives. 
+
+This allows for a background thread running a serial terminal in your program
+for debugging and state inspection consuming no CPU cycles at all. Not using
+this module will make that thread while(1) until data arrives.
+
+No code changes are needed for adding this module, all you need to do is to add
+it to EXTRA_COMPONENTS and add the directive configUSE_COUNTING_SEMAPHORES from
+FreeRTOSConfig.h in examples/terminal to your project.

extras/stdin_uart_interrupt/component.mk

@@ -0,0 +1,13 @@
+# Component makefile for extras/stdin_uart_interrupt
+#
+# See examples/terminal for usage. Well, actually there is no need to see it
+# for 'usage' as this module is a drop-in replacement for the original polled
+# version of reading from the UART.
+
+INC_DIRS += $(ROOT)extras/stdin_uart_interrupt
+
+# args for passing into compile rule generation
+extras/stdin_uart_interrupt_INC_DIR =  $(ROOT)extras/stdin_uart_interrupt
+extras/stdin_uart_interrupt_SRC_DIR =  $(ROOT)extras/stdin_uart_interrupt
+
+$(eval $(call component_compile_rules,extras/stdin_uart_interrupt))

extras/stdin_uart_interrupt/stdin_uart_interrupt.c

@@ -23,8 +23,6 @@
  */
 
 #include <esp8266.h>
-#include <espressif/esp8266/esp8266.h>
-#include <espressif/esp8266/uart_register.h>
 #include <FreeRTOS.h>
 #include <semphr.h>
 
@@ -35,36 +33,36 @@
 // 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
 
+#define UART0_RX_SIZE  (128) // ESP8266 UART HW FIFO size
+
 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)) {
+    if (!UART(UART0).INT_STATUS & UART_INT_STATUS_RXFIFO_FULL) {
         return;
     }
-    WRITE_PERI_REG(UART_INT_CLR(UART0), UART_RXFIFO_FULL_INT_CLR);
+//    printf(" [%08x (%d)]\n", READ_PERI_REG(UART_INT_ST(UART0)), READ_PERI_REG(UART_STATUS(UART0)) & (UART_RXFIFO_CNT << UART_RXFIFO_CNT_S));
-    while (READ_PERI_REG(UART_STATUS(UART0)) & (UART_RXFIFO_CNT << UART_RXFIFO_CNT_S)) {
+    if (UART(UART0).INT_STATUS & UART_INT_STATUS_RXFIFO_FULL) {
-        char ch = READ_PERI_REG(UART_FIFO(UART0)) & 0xff;
+        UART(UART0).INT_CLEAR = UART_INT_CLEAR_RXFIFO_FULL;
-        uint8_t wr_next = (wr_pos+1) % UART0_RX_SIZE;
+        if (UART(UART0).STATUS & (UART_STATUS_RXFIFO_COUNT_M << UART_STATUS_RXFIFO_COUNT_S)) {
-        if (wr_next != rd_pos) {
+            long int xHigherPriorityTaskWoken;
-            rx_buf[wr_pos] = ch;
+            _xt_isr_mask(1 << INUM_UART);
-            wr_pos = (wr_pos+1) % UART0_RX_SIZE;
+            _xt_clear_ints(1<<INUM_UART);
-            xSemaphoreGiveFromISR(uart0_sem, NULL);
+            xSemaphoreGiveFromISR(uart0_sem, &xHigherPriorityTaskWoken);
+            if(xHigherPriorityTaskWoken) {
+                portYIELD();
+            }
         }
+    } else {
+        printf("Error: unexpected uart irq, INT_STATUS 0x%02x\n", UART(UART0).INT_STATUS);
     }
 }
 
@@ -72,26 +70,23 @@ uint32_t uart0_num_char(void)
 {
     uint32_t count;
     if (!inited) uart0_rx_init();
-    _xt_isr_mask(1 << INUM_UART);
+    count = UART(UART0).STATUS & (UART_STATUS_RXFIFO_COUNT_M << UART_STATUS_RXFIFO_COUNT_S);
-    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
+// _read_r in core/newlib_syscalls.c will be skipped by the linker 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 (!(UART(UART0).STATUS & (UART_STATUS_RXFIFO_COUNT_M << UART_STATUS_RXFIFO_COUNT_S))) {
-        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;
+            if (!xSemaphoreTake(uart0_sem, portMAX_DELAY)) {
+                printf("\nFailed to get sem\n");
+            }
         }
+        ptr[i] = UART(UART0).FIFO & (UART_FIFO_DATA_M << UART_FIFO_DATA_S);
     }
     return len;
 }
@@ -104,16 +99,19 @@ static void uart0_rx_init(void)
     _xt_isr_attach(INUM_UART, uart0_rx_handler);
     _xt_isr_unmask(1 << INUM_UART);
 
-    //clear rx and tx fifo,not ready
+    // clear rx and tx fifo,not ready
-    SET_PERI_REG_MASK(UART_CONF0(UART0), UART_RXFIFO_RST | UART_TXFIFO_RST);
+    uint32_t conf = UART(UART0).CONF0;
-    CLEAR_PERI_REG_MASK(UART_CONF0(UART0), UART_RXFIFO_RST | UART_TXFIFO_RST);
+    UART(UART0).CONF0 = conf | UART_CONF0_RXFIFO_RESET | UART_CONF0_TXFIFO_RESET;
+    UART(UART0).CONF0 = conf & ~(UART_CONF0_RXFIFO_RESET | UART_CONF0_TXFIFO_RESET);
 
-    //set rx fifo trigger
+    // set rx fifo trigger
-    WRITE_PERI_REG(UART_CONF1(UART0), (trig_lvl & UART_RXFIFO_FULL_THRHD) << UART_RXFIFO_FULL_THRHD_S);
+    UART(UART0).CONF1 |= (trig_lvl & UART_CONF1_RXFIFO_FULL_THRESHOLD_M) << UART_CONF1_RXFIFO_FULL_THRESHOLD_S;
+
+    // clear all interrupts
+    UART(UART0).INT_CLEAR = 0x1ff;
+
+    // enable rx_interrupt
+    UART(UART0).INT_ENABLE = UART_INT_ENABLE_RXFIFO_FULL;
 
-    //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/stdin_uart_interrupt/stdin_uart_interrupt.h

@@ -22,12 +22,11 @@
  * THE SOFTWARE.
  */
 
-#ifndef __I2C_H__
+#ifndef __STDIN_UART_INTERRUPT_H__
-#define __I2C_H__
+#define __STDIN_UART_INTERRUPT_H__
-#endif
 
 #include <stdint.h>
-#include <stdbool.h>
 
 // Return number of characters waiting in UART0
 uint32_t uart0_num_char(void);
+#endif