UM6_usart.h

00001 /* ______________________________________________________________________________________
00002  File: UM6_usart.h
00003  Author: CH Robotics, adapted for mbed by lhiggs
00004  Version: 1.0
00005  
00006  Description: Function declarations for USART communucation
00007  -------------------------------------------------------------------------------------- */
00008  
00009  #ifndef _CHR_USART_H
00010  #define _CHR_USART_H
00011 
00012  #define  MAX_PACKET_DATA      40
00013  
00014  // Definitions of states for USART receiver state machine (for receiving packets)
00015  #define USART_STATE_WAIT       1
00016  #define USART_STATE_TYPE       2
00017  #define USART_STATE_ADDRESS    3
00018  #define USART_STATE_DATA       4
00019  #define USART_STATE_CHECKSUM   5
00020 
00021  // Flags for interpreting the packet type byte in communication packets
00022  #define PACKET_HAS_DATA            (1 << 7)
00023  #define PACKET_IS_BATCH            (1 << 6)
00024  #define PACKET_BATCH_LENGTH_MASK   ( 0x0F )
00025  
00026  #define PACKET_BATCH_LENGTH_OFFSET     2
00027  
00028  #define BATCH_SIZE_2                   2
00029  #define BATCH_SIZE_3                   3
00030  
00031  #define PACKET_NO_DATA                 0
00032  #define PACKET_COMMAND_FAILED      (1 << 0)
00033  
00034  
00035  // Define flags for identifying the type of packet address received
00036  #define ADDRESS_TYPE_CONFIG            0
00037  #define ADDRESS_TYPE_DATA              1
00038  #define ADDRESS_TYPE_COMMAND           2
00039  
00040  
00041 extern uint8_t gUSART_State;
00042 
00043  // Structure for storing TX and RX packet data
00044  typedef struct _USARTPacket
00045  {
00046         uint8_t PT;         // Packet type
00047         uint8_t address;    // Packet address
00048         uint16_t checksum;  // Checksum
00049         
00050         // Data included for convenience, but that isn't stored in the packet itself
00051         uint8_t data_length;  // Number of bytes in data section
00052         uint8_t address_type; // Specified the address type (DATA, CONFIG, OR COMMAND)
00053         
00054         uint8_t packet_data[MAX_PACKET_DATA];
00055         
00056  } USARTPacket;
00057  
00058 uint16_t ComputeChecksum( USARTPacket* new_packet );
00059 
00060 #endif