From d85f3aeeeefd6926fe71ec8e066adb74f62dc1cc Mon Sep 17 00:00:00 2001
From: fishsoupisgood <github@madingley.org>
Date: Sat, 13 Jun 2020 21:05:45 +0100
Subject: fish

---
 app/usart.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 app/usart.c

(limited to 'app/usart.c')

diff --git a/app/usart.c b/app/usart.c
new file mode 100644
index 0000000..177d165
--- /dev/null
+++ b/app/usart.c
@@ -0,0 +1,121 @@
+#include "project.h"
+
+#define BUFFER_SIZE 256
+#define BIG_BUFFER_SIZE 600
+
+ring_t rx1_ring;
+static uint8_t rx1_ring_buf[BUFFER_SIZE];
+
+ring_t tx1_ring;
+static uint8_t tx1_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);
+
+
+      ring_write_byte (&rx1_ring, 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 (&tx1_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 = len;
+
+      usart1_drain ();
+
+      while (len--)
+        {
+          if (*ptr == '\n')
+            ring_write_byte (&tx1_ring, '\r');
+          ring_write_byte (&tx1_ring, *(ptr++));
+        }
+
+      USART_CR1 (USART1) |= USART_CR1_TXEIE;
+      return ret;
+    }
+
+  errno = EIO;
+  return -1;
+}
+
+void
+usart1_queue (uint8_t d)
+{
+  ring_write_byte (&tx1_ring, d);
+  USART_CR1 (USART1) |= USART_CR1_TXEIE;
+}
+
+
+void
+usart1_drain (void)
+{
+  while (!ring_empty (&tx1_ring));
+}
+
+
+
+void
+usart_init (void)
+{
+  rcc_periph_clock_enable (RCC_USART1);
+
+  ring_init (&rx1_ring, rx1_ring_buf, sizeof (rx1_ring_buf));
+  ring_init (&tx1_ring, tx1_ring_buf, sizeof (tx1_ring_buf));
+
+  /* Enable the USART1,2 interrupt. */
+  nvic_enable_irq (NVIC_USART1_IRQ);
+
+  /* Map pins, and set usart2 to have pull ups */
+  gpio_set_mode (GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
+                 GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX);
+  gpio_set_mode (GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT,
+                 GPIO_USART1_RX);
+
+  /* Setup UART1 parameters. */
+  usart_set_baudrate (USART1, 115200);
+  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 USART1,2 Receive interrupt. */
+  USART_CR1 (USART1) |= USART_CR1_RXNEIE;
+
+  /* Finally enable the USARTs. */
+  usart_enable (USART1);
+}
-- 
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