ucmb: Add more documentation and example code for AVR8

git-svn-id: svn://svn.openwrt.org/openwrt/packages@14564 3c298f89-4303-0410-b956-a3cf2f4a3e73

utils/ucmb/microcontroller_examples/atmel_avr8/ucmb.h

@@ -0,0 +1,24 @@
+#ifndef UCMB_AVR8_H_
+#define UCMB_AVR8_H_
+
+#include <stdint.h>
+
+
+/* Max length of the message payload. */
+#define UCMB_MAX_MSG_LEN	0x200
+
+/* ucmb_rx_message - Message receive callback.
+ * Define this elsewhere. It's called on successful retrieval
+ * of a new message.
+ * If a reply message has to be transferred after this one, put the
+ * message payload into the "payload" buffer and return the number
+ * of bytes to transmit. If no reply message is needed, return 0.
+ * Note that the "payload" buffer always has a size of UCMB_MAX_MSG_LEN.
+ */
+extern uint16_t ucmb_rx_message(uint8_t *payload,
+				uint16_t payload_length);
+
+/* Initialize the UCMB subsystem. */
+void ucmb_init(void);
+
+#endif /* UCMB_AVR8_H_ */