DcAN I/O Interface

Data can be passed between a client and a DcAN I/O device through the DcAN I/O Interface. Packets are sent through a TCP/IP port. The following rules apply:

• The I/O device shall listen for TCP/IP connections on IP port number 33001
• A maximum of 3 clients can simultaneously connect to the DcAN I/O Interface port
• All elements of each packet shall be in network byte order

The following sections define the packets that are valid for the DcAN I/O Interface

I2C Read Request

• Each element of the I2C Read Request Packet is a 16 bit unsigned integer
• The first 16 bit word of the packet represents the unique identifier and must be equal to 0x301
• An I2C Read Response Packet with the requested data will be sent back to the client in response to each I2C Read Request

Byte Offset	Element	Notes
0	0x301
2	Request ID	Arbitrary value that will be sent back in the response
4	I2C Bus ID	0=I2C Bus 'A' 1=I2C Bus 'B'
6	# Bytes to Read
8	I2C Address
10	Read Mode	0=One-time read 1=Periodic 2=On Change + Periodic
12	Periodic Read Frequency	millseconds

I2C Read Response

• Each element of the I2C Read Response Packet is a 16 bit unsigned integer
• The first 16 bit word of the packet represents the unique identifier and must be equal to 0x302
• An I2C Read Response Packet is sent to the client in response to an I2C Read Request

Byte Offset	Element
0	0x302
2	Request ID
4	I2C Bus ID
6	# Bytes Returned
8	Data Returned from I2C

I2C Write

• The first 10 bytes of the I2C Write Packet are 16 bit unsigned integers
• The first 16 bit word of the packet represents the unique identifier and must be equal to 0x303

Byte Offset	Element
0	0x303
2	Request ID
4	I2C Bus ID
6	# Bytes to Write
8	I2C Address
10...	Bytes to be Written

Write Display Pixel Data

• The first 14 bytes of the Write Display Data Packet are 16 bit unsigned integers
• The first 16 bit word of the packet represents the unique identifier and must be equal to 0x304

Byte Offset	Element
0	0x304
2	I2C Bus ID
4	I2C Address
6	Beginning Pixel Column
8	Beginning Pixel Row
10	Total Number of Pixel Columns
12	Total Number of Pixel Rows
14...	Array of Pixel Columns and Rows (8 pixels per byte)