added a single-byte uart interface
diff --git a/bbb_cape/src/cape/uart_byte.h b/bbb_cape/src/cape/uart_byte.h
new file mode 100644
index 0000000..7aa7f43
--- /dev/null
+++ b/bbb_cape/src/cape/uart_byte.h
@@ -0,0 +1,17 @@
+#ifndef CAPE_UART_BYTE_H_
+#define CAPE_UART_BYTE_H_
+
+#include <stdint.h>
+
+// uart_common_configure must be called before this.
+void uart_byte_configure(void);
+
+// Spins until 1 byte is received or some amount of time. The timeout is
+// timeout_count*timeout_divider/30MHz.
+// The result is <0 for timeout or the received byte.
+int uart_byte_receive(uint16_t timeout_count, uint16_t timeout_divider);
+
+// Spins until 1 byte can be written out.
+void uart_byte_send(uint8_t value);
+
+#endif // CAPE_UART_BYTE_H_