SMU-Communication-Backend

The Communication Backend for the Universal-I2C-Sensor-Master-Unit.

General Message Formate

All serial messages used to controll the SMU board follow the following format:

|-----------------|-------------|-------------|----------------------|----------|-----------------|
| '~' as Preambel | MessageType | PayloadSize | 0 - 25 Bytes of Data | Checksum | '#' as End-Sign |
|      1 Char     |   1 Byte    |    1 Byte   |     0 - 25 Bytes     |  1 Byte  |      1 Char     |
|-----------------|-------------|-------------|----------------------|----------|-----------------|

MessageType

Dec-Code	Hex-Code	MessageType	Data Bytes	Description
-1	0xff	ERROR	additional information (up to 25 bytes)	message type to indicate an error
0	0x00	NONE	-	empty message -> no message
1	0x01	ACK_FAULT	8-bit message-type of last rec message + error code	Indicates a coomunication error
2	0x02	ACK	8-bit message-type that is been acknowledged + payload	ACK + payload send back (can be up to 24 bytes)
3	0x03	PONG	8-bit random value	Ping Request
4	0x04	G_STATUS	-	Get the current system stauts code from the SMU
5	0x05	G_COM_ERROR	-	Get the current comunication error code from the SMU
6	0x09	G_SMU_ERROR	-	Get the current SMU error code from the SMU
9	0x09	RESET	-	Perform a soft reset of the SMU
10	0x0a	FIRMWARE_V	-	Request the firmware-version of the SMU
11	0x0b	COM_BACK_V	-	Request the communication backend version of the SMU
30	0x1e	INIT_SENSOR	8-bit sensor-type + 8-bit sensor port	Starts the initialization of a sensor at a given new port
31	0x1f	S_SENS_ACTIVE	8-bit sensor no. + 8-bit status (1 or 0)	Activates or deactivates a sensor
32	0x20	G_SENS_ACTIVE	8-bit sensor no.	Get the activation status of an sensor
70	0x46	S_AUTO_UPDATE	8-bit status (1 or 0)	Activates or deactivates the automatic sensor update
71	0x47	G_AUTO_UPDATE	-	Get the activation stauts of the auto update
72	0x48	MAN_UPDATE	8-bit sensor no.	Performs a manual update of the given sensor
100	0x64	READ_SENSOR	8-bit sensor no.	Request the sensor reading of the specified sensor

Message Flow

Requested	Answer?	MessageType of Answer	Data Bytes of Answer	Payload-Size [bytes]
NONE	no	-	-	-
ACK_FAULT	no	-	-	-
ACK	no	-	-	-
PONG	yes	ACK	PONG + 8-bit random value from request	1 + 1 = 2
G_STATUS	yes	ACK	G_STATUS + 16-bit status code	1 + 2 = 3
G_COM_ERROR	yes	ACK	G_COM_ERROR + 16-bit communication error code	1 + 2 = 3
G_SMU_ERROR	yes	ACK	G_SMU_ERROR + 16-bit SMU error code	1 + 2 = 3
RESET	yes	ACK	RESET	1
FIRMWARE_V	yes	ACK	FIRMWARE_V + 16-bit version	1 + 1 = 2
COM_BACK_V	yes	ACK	COM_BACK_V + 16-bit version	1 + 1 = 2
INIT_SENSOR	yes	ACK	INIT_SENSOR + success byte (1 or 0) + assigned 8-bit sensor no.	1 + 2 = 3
S_SENS_ACTIVE	yes	ACK	S_SENS_ACTIVE + success byte (1 or 0)	1 + 1 = 2
G_SENS_ACTIVE	yes	ACK	G_SENS_ACTIVE + success byte (1 or 0) + activation status byte (1 or 0)	1 + 2 = 3
S_AUTO_UPDATE	yes	ACK	G_AUTO_UPDATE + success byte (1 or 0)	1 + 1 = 2
G_AUTO_UPDATE	yes	ACK	S_AUTO_UPDATE + success byte (1 or 0) + activation status byte (1 or 0)	1 + 1 = 2
MAN_UPDATE	yes	ACK	MAN_UPDATE + success byte (1 or 0)	1 + 1 = 2
READ_SENSOR	yes	ACK	READ_SENSOR + success byte (1 or 0) + array of sensor readings	up to 25

If the format of a received message is incorrect or the checksum does not match, the following must be answered:

MessageType of Answer	Data Bytes of Answer	Payload-Size [bytes]
ACK_FAULT	received message type + communication error information	up to 25

communication error information

Error Code	Error Code [HEX]	Error Description	Data Bytes
NO_COM_ERROR	0x00	no error	-
NO_START_SIGN	0x01	no start sign was found	-
NO_END_SING	0x02	no end sign was found	opt. rec. msg. type
INV_PAYL_SIZE	0x03	the payload-size is invalid	opt. rec. msg. type + opt. rec. payload-size
INV_CHECKSUM	0x04	the checksum is invalid	opt. rec. msg. type + opt. rec. checksum + opt. calc. checksum
NOT_ENOUGH_DATA	0x05	not enough data bytes received	opt. rec. msg. type + opt. overall rec. number of bytes
REC_TIMEOUT	0x06	timeout during rec of data	opt. rec. msg. type + opt. overall rec. number of bytes