UART: Add ability to configure stopbits and parity bit (#590)

core/include/esp/uart.h

@@ -124,4 +124,40 @@ static inline int uart_get_baud(int uart_num)
     return APB_CLK_FREQ / FIELD2VAL(UART_CLOCK_DIVIDER_VALUE, UART(uart_num).CLOCK_DIVIDER);
 }
 
+/* Set uart stop bit count to the desired value */
+static inline void uart_set_stopbits(int uart_num, UART_StopBits stop_bits) {
+    UART(uart_num).CONF0 = SET_FIELD(UART(uart_num).CONF0, UART_CONF0_STOP_BITS, stop_bits);
+}
+
+/* Returns the current stopbit count for the UART */
+static inline UART_StopBits uart_get_stopbits(int uart_num) {
+    return (UART_StopBits)(FIELD2VAL(UART_CONF0_STOP_BITS, UART(uart_num).CONF0));
+}
+
+/* Set if uart parity bit should be enabled */
+static inline void uart_set_parity_enabled(int uart_num, bool enable) {
+    if(enable)
+        UART(uart_num).CONF0 = SET_MASK_BITS(UART(uart_num).CONF0, UART_CONF0_PARITY_ENABLE);
+    else
+        UART(uart_num).CONF0 = CLEAR_MASK_BITS(UART(uart_num).CONF0, UART_CONF0_PARITY_ENABLE);
+}
+
+/* Set uart parity bit type */
+static inline void uart_set_parity(int uart_num, UART_Parity parity) {
+    if(parity == UART_PARITY_EVEN)
+        UART(uart_num).CONF0 = CLEAR_MASK_BITS(UART(uart_num).CONF0, UART_CONF0_PARITY);
+    else
+        UART(uart_num).CONF0 = SET_MASK_BITS(UART(uart_num).CONF0, UART_CONF0_PARITY);
+}
+
+/* Returns if parity bit is currently enabled for UART uart_num */
+static inline bool uart_get_parity_enabled(int uart_num) {
+    return ((UART(uart_num).CONF0 & UART_CONF0_PARITY_ENABLE) != 0);
+}
+
+/* Returns the current parity bit type for UART uart_num (also if parity bit is not enabled) */
+static inline UART_Parity uart_get_parity(int uart_num) {
+    return (UART_Parity)((UART(uart_num).CONF0 & UART_CONF0_PARITY) != 0);
+}
+
 #endif /* _ESP_UART_H */

core/include/esp/uart_regs.h

@@ -50,6 +50,18 @@ struct UART_REGS {
 
 _Static_assert(sizeof(struct UART_REGS) == 0x80, "UART_REGS is the wrong size");
 
+typedef enum {
+    UART_STOPBITS_0 = 0b00,
+    UART_STOPBITS_1 = 0b01,
+    UART_STOPBITS_1_5 = 0b10,
+    UART_STOPBITS_2 = 0b11
+} UART_StopBits;
+
+typedef enum {
+    UART_PARITY_EVEN = 0b0,
+    UART_PARITY_ODD = 0b1
+} UART_Parity;
+
 /* Details for FIFO register */
 
 #define UART_FIFO_DATA_M  0x000000ff
@@ -153,7 +165,7 @@ _Static_assert(sizeof(struct UART_REGS) == 0x80, "UART_REGS is the wrong size");
 #define UART_CONF0_BYTE_LEN_M                0x00000003
 #define UART_CONF0_BYTE_LEN_S                2
 #define UART_CONF0_PARITY_ENABLE             BIT(1)
-#define UART_CONF0_PARITY                    BIT(0) //FIXME: does this indicate odd or even?
+#define UART_CONF0_PARITY                    BIT(0) //where 0 means even
 
 /* Details for CONF1 register */
 

examples/uart_config/Makefile

@@ -0,0 +1,3 @@
+PROGRAM=uart_config
+
+include ../../common.mk

examples/uart_config/uart_config.c

@@ -0,0 +1,96 @@
+/* A basic example that demonstrates how UART can be configured.
+   Outputs some test data with 100baud, 1.5 stopbits, even parity bit to UART1
+   (GPIO2; D4 for NodeMCU boards)
+
+   This sample code is in the public domain.
+ */
+
+#include <espressif/esp_common.h>
+#include <FreeRTOS.h>
+#include <task.h>
+#include <queue.h>
+
+#include <esp/uart.h>
+#include <esp/uart_regs.h>
+
+void uart_send_data(void *pvParameters){
+    /* Activate UART for GPIO2 */
+    gpio_set_iomux_function(2, IOMUX_GPIO2_FUNC_UART1_TXD);
+    
+    /* Set baud rate of UART1 to 100 (so it's easier to measure) */
+    uart_set_baud(1, 100);
+    
+    /* Set to 1.5 stopbits */
+    uart_set_stopbits(1, UART_STOPBITS_1_5);
+    
+    /* Enable parity bit */
+    uart_set_parity_enabled(1, true);
+    
+    /* Set parity bit to even */
+    uart_set_parity(1, UART_PARITY_EVEN);
+    
+    /* Repeatedly send some example packets */
+    for(;;)
+    {
+        uart_putc(1, 0B00000000);
+        uart_putc(1, 0B00000001);
+        uart_putc(1, 0B10101010);
+        uart_flush_txfifo(1);
+    }
+}
+
+void uart_print_config(void *pvParameters){
+    for(;;)
+    {
+        /* Get data */
+        int baud = uart_get_baud(1);
+        UART_StopBits stopbits = uart_get_stopbits(1);
+        bool parity_enabled = uart_get_parity_enabled(1);
+        UART_Parity parity = uart_get_parity(1);
+        
+        /* Print to UART0 */
+        printf("Baud: %d ", baud);
+        
+        switch(stopbits){
+        case UART_STOPBITS_0:
+            printf("Stopbits: 0 ");
+        break;
+        case UART_STOPBITS_1:
+            printf("Stopbits: 1 ");
+        break;
+        case UART_STOPBITS_1_5:
+            printf("Stopbits: 1.5 ");
+        break;
+        case UART_STOPBITS_2:
+            printf("Stopbits: 2");
+        break;
+        default:
+            printf("Stopbits: Error");
+        }
+        
+        printf("Parity bit enabled: %d ", parity_enabled);
+        
+        switch(parity){
+        case UART_PARITY_EVEN:
+            printf("Parity: Even");
+        break;
+        case UART_PARITY_ODD:
+            printf("Parity: Odd");
+        break;
+        default:
+            printf("Parity: Error");
+        }
+        
+        printf("\n");
+        
+        vTaskDelay(1000.0 / portTICK_PERIOD_MS);
+    }
+}
+
+void user_init(void){
+    uart_set_baud(0, 115200);
+    printf("SDK version:%s\n", sdk_system_get_sdk_version());
+    
+    xTaskCreate(uart_send_data, "tsk1", 256, NULL, 2, NULL);
+    xTaskCreate(uart_print_config, "tsk2", 256, NULL, 3, NULL);
+}