1 files changed, 127 insertions, 0 deletions
diff --git a/libraries/usart.c b/libraries/usart.c
new file mode 100644
index 0000000..61de99c
--- /dev/null
+++ b/libraries/usart.c
@@ -0,0 +1,127 @@
+
+
+#include "usart.h"
+
+
+extern USART usart3;
+
+
+// init functions
+
+void usart_init(USART *usart)
+{
+    // clock config
+    rcc_periph_clock_enable(RCC_GPIOB);  // for USART3
+    rcc_periph_clock_enable(RCC_USART3);  // for USART3
+
+    // gpio config
+    gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART3_TX);  // TX setup
+    gpio_set_mode(GPIOB, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO_USART3_RX);  // RX setup
+
+    // nvic config
+    nvic_enable_irq(NVIC_USART3_IRQ);
+    usart_enable_rx_interrupt(USART3);
+
+    // usart config
+    usart_set_baudrate(USART3, 9600);
+    usart_set_databits(USART3, 8);
+    usart_set_flow_control(USART3, USART_FLOWCONTROL_NONE);
+    usart_set_mode(USART3, USART_MODE_TX_RX);
+    usart_set_parity(USART3, USART_PARITY_NONE);
+    usart_set_stopbits(USART3, USART_STOPBITS_1);
+    usart_enable(USART3);
+
+    // fifo init
+    fifo_init(&usart->rx_fifo, USART_BUFFER_SIZE);
+    fifo_init(&usart->tx_fifo, USART_BUFFER_SIZE);
+}
+
+void usart_deinit(USART *usart)
+{
+    fifo_deinit(&usart->rx_fifo);
+    fifo_deinit(&usart->tx_fifo);
+}
+
+
+// write functions
+
+uint16_t usart_write_bytes(USART *usart, uint8_t *data_source, uint16_t data_length){
+    if ((data_length + fifo_bytes_available(&usart->tx_fifo)) <= fifo_get_buffersize(&usart->tx_fifo)){
+        for (int i=0; i<data_length; i++){
+            fifo_put_byte(&usart->tx_fifo, &data_source[i]);
+        }
+        usart_enable_tx_interrupt(USART3);
+        return data_length;
+    }
+    else{
+        return 0;
+    }
+}
+
+uint16_t usart_write(USART *usart, char *str)
+{
+    for (uint16_t i=0; i<(uint16_t)strlen(str); i++){
+        usart_write_bytes(usart, (uint8_t *)&str[i], 1);
+    }
+    return (uint16_t)strlen(str);
+}
+//uint16_t usart_writeln(USART *usart, char *str);
+
+
+// read functions
+
+uint16_t usart_read_bytes(USART *usart, uint8_t *data_sink, uint16_t data_length)
+{
+    if (data_length <= fifo_bytes_available(&usart->rx_fifo)){
+        for (int i=0; i<data_length; i++){
+            fifo_get_byte(&usart->rx_fifo, &data_sink[i]);
+        }
+        return data_length;
+    }
+    else{
+        return 0;
+    }
+}
+//uint16_t usart_read(USART *usart, char *data_sink, uint16_t data_length);
+//uint16_t usart_readln(USART *usart, char *data_sink);
+
+
+// usart isr
+
+void usart3_isr(void)
+{
+
+	/* Check if we were called because of RXNE. */
+	if (((USART_CR1(USART3) & USART_CR1_RXNEIE) != 0) &&
+		((USART_SR(USART3) & USART_SR_RXNE) != 0)) {
+
+		/* Retrieve the data from the peripheral. */
+		uint8_t data = usart_recv(USART3);
+        fifo_put_byte(&usart3.rx_fifo, &data);
+
+		/* Enable transmit interrupt so it sends back the data. */
+		//USART_CR1(USART3) |= USART_CR1_TXEIE;
+	}
+
+	/* Check if we were called because of TXE. */
+	if (((USART_CR1(USART3) & USART_CR1_TXEIE) != 0) &&
+		((USART_SR(USART3) & USART_SR_TXE) != 0)) {
+
+		/* Put data into the transmit register. */
+        if (fifo_bytes_available(&usart3.tx_fifo)){
+            uint8_t data;
+            fifo_get_byte(&usart3.tx_fifo, &data);
+            usart_send(USART3, data);
+            if(data == '\r'){
+                uint8_t nl = (uint8_t)'\n';
+                usart_write_bytes(&usart3, &nl, 1);
+            }
+            if (fifo_bytes_available(&usart3.tx_fifo)){
+                usart_enable_tx_interrupt(USART3);
+            }
+            else{
+                usart_disable_tx_interrupt(USART3);
+            }
+        }
+    }
+}