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authorroot <root@lab2.panaceas.james.local>2014-11-02 18:17:44 +0000
committerroot <root@lab2.panaceas.james.local>2014-11-02 18:17:44 +0000
commit12287ff0a55f929bf840dcb4780d3f77b862c434 (patch)
tree46632674f393249e7cd74eacd7a4da00ccec540f /app/usart.c
parent479e719a64d75374f00438498cf91ba2601a63f1 (diff)
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Diffstat (limited to 'app/usart.c')
-rw-r--r--app/usart.c104
1 files changed, 104 insertions, 0 deletions
diff --git a/app/usart.c b/app/usart.c
new file mode 100644
index 0000000..f510682
--- /dev/null
+++ b/app/usart.c
@@ -0,0 +1,104 @@
+#include "project.h"
+
+#define BUFFER_SIZE 256
+
+static ring_t output_ring;
+static uint8_t output_ring_buf[BUFFER_SIZE];
+
+void
+usart1_isr (void)
+{
+ uint8_t data;
+
+ /* Check if we were called because of RXNE. */
+ if (((USART_CR1 (USART1) & USART_CR1_RXNEIE) != 0) &&
+ ((USART_SR (USART1) & USART_SR_RXNE) != 0))
+ {
+
+ /* Retrieve the data from the peripheral. */
+ data = usart_recv (USART1);
+
+ kvm_recv (data);
+ }
+
+ /* Check if we were called because of TXE. */
+ if (((USART_CR1 (USART1) & USART_CR1_TXEIE) != 0) &&
+ ((USART_SR (USART1) & USART_SR_TXE) != 0))
+ {
+
+ if (ring_read_byte (&output_ring, &data))
+ {
+ /*No more data, Disable the TXE interrupt, it's no longer needed. */
+ USART_CR1 (USART1) &= ~USART_CR1_TXEIE;
+ }
+ else
+ {
+ usart_send (USART1, data);
+ }
+ }
+
+}
+
+int
+_write (int file, char *ptr, int len)
+{
+ int ret;
+
+ if (file == 1)
+ {
+ ret = ring_write (&output_ring, (uint8_t *) ptr, len);
+
+ if (ret < 0)
+ ret = -ret;
+
+ USART_CR1 (USART1) |= USART_CR1_TXEIE;
+ return ret;
+ }
+
+ errno = EIO;
+ return -1;
+}
+
+void
+usart_queue (uint8_t d)
+{
+ ring_write_byte (&output_ring, d);
+ USART_CR1 (USART1) |= USART_CR1_TXEIE;
+
+#if 0
+ printf ("0x%02x ", d);
+ fflush (stdout);
+#endif
+}
+
+
+void
+usart_init (void)
+{
+ ring_init (&output_ring, output_ring_buf, sizeof (output_ring_buf));
+
+ /* Enable the USART1 interrupt. */
+ nvic_enable_irq (NVIC_USART1_IRQ);
+
+ /* Setup GPIO pin GPIO_USART1_RE_TX on GPIO port B for transmit. */
+ gpio_set_mode (GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
+ GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX);
+
+ /* Setup GPIO pin GPIO_USART1_RE_RX on GPIO port B for receive. */
+ gpio_set_mode (GPIOA, GPIO_MODE_INPUT,
+ GPIO_CNF_INPUT_FLOAT, GPIO_USART1_RX);
+
+ /* Setup UART parameters. */
+ usart_set_baudrate (USART1, 38400);
+ usart_set_databits (USART1, 8);
+ usart_set_stopbits (USART1, USART_STOPBITS_1);
+ usart_set_parity (USART1, USART_PARITY_NONE);
+ usart_set_flow_control (USART1, USART_FLOWCONTROL_NONE);
+ usart_set_mode (USART1, USART_MODE_TX_RX);
+
+ /* Enable USART1 Receive interrupt. */
+ USART_CR1 (USART1) |= USART_CR1_RXNEIE;
+
+ /* Finally enable the USART. */
+ usart_enable (USART1);
+}