200 lines
9.1 KiB
C
200 lines
9.1 KiB
C
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///////////////////////////////////////////////////////////
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//
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// This file is part of RTArduLink
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//
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// Copyright (c) 2014-2015 richards-tech
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//
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// Permission is hereby granted, free of charge,
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// to any person obtaining a copy of
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// this software and associated documentation files
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// (the "Software"), to deal in the Software without
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// restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute,
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// sublicense, and/or sell copies of the Software, and
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// to permit persons to whom the Software is furnished
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// to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice
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// shall be included in all copies or substantial portions
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// of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
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// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
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// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
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// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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// The RTArduLink communications protocol works by exchanging frames across the host <-> subsystem interface.
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// The structure RTARDULINK_FRAME defines the frame structure. There is a 4 byte header for frame level control
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// while the remainder is available for higher level message. Note that the structure implies fixed length
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// buffers which works well with the subsystem however only the number of bytes actually used are transferred
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// across the interface.
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//
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// Note that there is no flow control at the frame level - it is assumed that the higher level interactions host -> subsystem
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// are window 1 acknowledged transfers so that the maximum possible unprocessed frames is equal to the number
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// of higher level services. Subsystem -> host transfers are always either responses to host commands or else regular
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// status updates so the rate from subsystem to host is controlled by configuration.
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//
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// The frame integrity is protected by a single byte checksum. To keep things very simple, it is the 2s complement
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// of the 8 bit sum of all the bytes in the message array. This is used in conjunction with 0xAA and 0x55 bytes
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// to determine correct sync (in case of lost bytes which should not really happen!).
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//
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// Frame sync is obtained by reading bytes until the 0xAA pattern is seen. If the next byte is not 0x55, keep
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// scanning. If it is, assume this byte is messageLength and the next one is the frameCksm value. Read in the
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// message array based on messageLength and then calculate the checksum. If the checksum is correct, sync has been
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// obtained and the message is valid. Otherwise, start looking for an 0xAA value again.
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#ifndef _RTARDULINKDEFS_H
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#define _RTARDULINKDEFS_H
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// Some defines to cope with compiler differences
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#ifndef __cplusplus
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#ifndef false
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#define false 0
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#endif
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#ifndef true
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#define true 1
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#endif
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typedef unsigned char bool;
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#endif
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#ifndef NULL
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#define NULL 0
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#endif
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// Some general purpose typedefs - used especially for transferring values greater than
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// 8 bits across the link and avoids endian issues. Assumes processor has 32 bit ints!
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typedef unsigned char RTARDULINK_UC2[2]; // an array of two unsigned chars
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typedef unsigned char RTARDULINK_UC4[4]; // an array of four unsigned chars
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// Port speed codes
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#define RTARDULINK_PORT_SPEED_OFF 0 // port is unused
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#define RTARDULINK_PORT_SPEED_9600 1 // 9600 baud
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#define RTARDULINK_PORT_SPEED_19200 2 // 19200 baud
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#define RTARDULINK_PORT_SPEED_38400 3 // 38400 baud
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#define RTARDULINK_PORT_SPEED_57600 4 // 57600 baud
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#define RTARDULINK_PORT_SPEED_115200 5 // 115200 baud
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#define RTARDULINK_PORT_SPEED_COUNT 6 // six codes total
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extern unsigned long RTArduLinkSpeedMap[];
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//------------------------------------------------------------------------------------------------------
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//
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// Frame level defs and structure
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#define RTARDULINK_FRAME_MAX_LEN 64 // maximum possible length of a frame
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#define RTARDULINK_FRAME_HEADER_LEN 4 // 4 bytes in frame header (must correspond with the structure below!)
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#define RTARDULINK_MESSAGE_HEADER_LEN 4 // 4 bytes in message header (must correspond with the structure below!)
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#define RTARDULINK_MESSAGE_MAX_LEN (RTARDULINK_FRAME_MAX_LEN - RTARDULINK_FRAME_HEADER_LEN) // max length of message
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#define RTARDULINK_DATA_MAX_LEN (RTARDULINK_MESSAGE_MAX_LEN - RTARDULINK_MESSAGE_HEADER_LEN)// max length of data field
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#define RTARDULINK_MESSAGE_SYNC0 0xAA
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#define RTARDULINK_MESSAGE_SYNC1 0x55
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#define RTARDULINK_MY_ADDRESS 0 // the subsystem address for local processing
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#define RTARDULINK_BROADCAST_ADDRESS 0xffff // the subsystem address for all subsystems
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#define RTARDULINK_ADDRESSES 0x1000 // number of addresses
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// RTARDULINK_MESSAGE is carried in the RTARDULINK_FRAME
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//
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// The messageAddress field allows subsystems to be daisy-chained. Valid addresses are 0 to 65534.
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// Address 65535 is a broadcast and goes to all subsystems.
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// Every message has the messageType and messageParam bytes but there can be from 0 to 56 bytes of data
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typedef struct
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{
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RTARDULINK_UC2 messageAddress; // subsystem message address
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unsigned char messageType; // message type code
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unsigned char messageParam; // an optional parameter to the message type
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unsigned char data[RTARDULINK_DATA_MAX_LEN]; // the actual data! Length is computed from messageLength.
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} RTARDULINK_MESSAGE;
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// RTARDULINK_FRAME is the lowest level structure used across the RTArduLink
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typedef struct
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{
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unsigned char sync0; // sync0 code
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unsigned char sync1; // sync1 code
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unsigned char messageLength; // the length of the message in the message field - between 4 and 60 bytes
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unsigned char frameChecksum; // checksum for frame
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RTARDULINK_MESSAGE message; // the actual message
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} RTARDULINK_FRAME;
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// RTARDULINK_RXFRAME is a type that is used to reassemble a frame from a stream of bytes in conjunction with RTArduLinkReassemble()
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typedef struct
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{
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RTARDULINK_FRAME *frameBuffer; // the frame buffer pointer
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int length; // current length of frame
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int bytesLeft; // number of bytes needed to complete
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bool complete; // true if frame is complete and correct (as far as checksum goes)
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} RTARDULINK_RXFRAME;
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// Message types
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// RTARDULINK_MESSAGE_POLL
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//
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// The host should poll the RTArduLink at every RTARDULINK_POLL_INTERVAL.
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// The subsystem will respond by echoing the poll message as received.
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#define RTARDULINK_MESSAGE_POLL 0 // poll message
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// RTARDULINK_MESSAGE_IDENTIFY
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//
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// The host can send this message to request an identity string from the subsystem.
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// Only the messageType field is used in the request host -> subsystem. The subsystem
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// responds with an identity string in the data field.
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#define RTARDULINK_MESSAGE_IDENTITY 1 // identity message
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// RTARDULINK_MESSAGE_DEBUG
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//
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// This can be used to send a debug message up to the host. The data field contains a debug message
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#define RTARDULINK_MESSAGE_DEBUG 2 // debug message
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// RTARDULINK_MESSAGE_INFO
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//
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// This can be used to send an info message up to the host. The data field contains the message
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#define RTARDULINK_MESSAGE_INFO 3 // info message
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// RTARDULINK_MESSAGE_ERROR
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//
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// This code is returned by the subsystem if it received a message with an illegal message type
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// The first byte of the data is the error code. The rest of the data field depends on the error.
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#define RTARDULINK_MESSAGE_ERROR 4 // illegal message type response
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// RTARDULINK_MESSAGE_ECHO
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//
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// This message can be used to test link performance. The addressed subsystem just returns
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// the entire message to the host.
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#define RTARDULINK_MESSAGE_ECHO 5 // echo message
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// RTARDULINK_MESSAGE_CUSTOM
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//
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// This is the first message code that should be used for custom messages 16-255 are available.
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#define RTARDULINK_MESSAGE_CUSTOM 16 // start of custom messages
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// RTArduLink response codes
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#define RTARDULINK_RESPONSE_OK 0 // means things worked
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#define RTARDULINK_RESPONSE_ILLEGAL_COMMAND 1 // not a supported message type, data[1] has offending type
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#endif // _RTARDULINKDEFS_H
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