S-7600A Datasheet, PDF (54/60 Pages) Seiko Instruments Inc – Hardware Specification (TCP/IP Network Stack LSI)

TCP/IP Network Stack LSI
S-7600A
Hardware Specification Revision 1.3
8.3.2. UDP Data Communications
UDP data communications are performed if the SCTL-bit of the Serial Port Config register (0x08) is set to
“1.”
For data transmission, data is written to the Socket Data register (0x2E). The S-7600A stores data in its
outgoing buffer via the Socket Data register. The address of the outgoing buffer is specified by the Buffer
Out Length register (0x30-0x31). The value of the Buffer Out Length register is 0x03ff when the outgoing
buffer is empty. The value of the Buffer Out Length register decrements each time a byte of data is
written to the Socket Data register (0x2E). After the data is written, if any data is written to the TCP Data
Send register (0x30), the data stored in the outgoing buffer is processed by UDP protocols and
transmitted. Since the value of the Buffer Out Length register increases by the value of the number of
bytes of transmitted data, it is reset to 0x03ff when all data has been sent. For UDP data transmission,
the outgoing buffer can hold up to 1015 bytes of data. Datagrams longer than 1015 bytes are split by the
MPU and transmitted in chunks. When the outgoing buffer accumulates 1015 bytes of data, the value of
the Buffer Out Length register becomes 0x0008. No more than 1015 bytes of data are permitted in the
Socket Data register. Since this condition is not indicated by the Buff_Full bit in the Socket Config Status
Low register (0x22) or by the Buff_Full bit in the Socket Interrupt Low register (0x2C), the Buffer Out
Length register must be monitored, or supervised in the application layer. If data is written to the TCP
Data Send register under these conditions, the data in the outgoing buffer is transmitted. The MPU
repeats the procedure of sending residual data after checking that the Buffer Out Length register has
been restored to 0x03ff. The transmission of all data in the outgoing buffer can be confirmed by checking
the Buff_Empty bit in the Socket Config Status Low register (0x22) and the Buff_Empty bit in the Socket
Interrupt Low register (0x2C) following an interrupt.
When the S-7600A receives UDP data, it applies UDP protocol processing and stores the processed
data in the incoming buffer after adding 12 bytes of header information. Data reception can be
determined by checking whether the value of the Buffer In Length register equals 0x0000 or a different
value. The Data_Avail bit in the Socket Config Status Low register (0x22), the Socket Data Available
register (0x28), and the Data_Avail bit following an interrupt in the Socket Interrupt Low register (0x2C)
can all indicate data reception. Read the Socket Data register (0x2E) while monitoring the Data_Avail bit
in the Socket Config Status Low register. This fetches the 12 byte header from the incoming buffer,
followed by the data. Table 8-2 shows the header structure.
8-4
Seiko Instruments Inc.