Sundance SMT911 - Manual (Page 14)

SMT911 User Manual SMT911 Page 14 of 38 Last Edited: 01/06/2010 10:09:00
streaming speed of 250MB/s is possible, or burst transfers of 500MB/s (not taking
overhead into consideration). It also receives direct control words from the DSP
module, by getting the forwarded control worlds from the “SMT_control” module.
This block is supported by a DDR2 RAM interface available on the SMT351T board
for continuous playback in TX mode or as a buffer in RX mode.
These registers control the complete functionality of the SMT911 transceiver
mezzanine. They are set up via the Comport 3 of the base module.
The data passed to the FPGA over the Comports must conform to a certain packet
structure. Only after a valid packet is accepted and an update command sent will
the specified settings be applied. The packet structure is illustrated in the following
table.
Packet structure for writing (Byte 0 = 0x10)
Byte Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
0 “0” “0” “0” “1” “0” “0” “0” “0”
1 Address7 Address6 Address5 Address4 Address3 Address2 Address1 Address0
2 Data15 Data14 Data13 Data12 Data11 Data10 Data9 Data8
3 Data7 Data6 Data5 Data4 Data3 Data2 Data1 Data0
Packet structure for reading (Byte 0 = 0x20)
Byte Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
0 “0” “0” “1” “0” “0” “0” “0” “0”
1 Address7 Address6 Address5 Address4 Address3 Address2 Address1 Address0
2 Data15 Data14 Data13 Data12 Data11 Data10 Data9 Data8
3 Data7 Data6 Data5 Data4 Data3 Data2 Data1 Data0
Byte 0 of a packet must be 0x10 (for writing register) or 0x20 (for reading register).
This byte indicates the start of a packet and is required to synchronize
communication. Byte 1 denotes the register address to be accessed. Byte 2 is the
upper 8 bits of the data to the written or read, and Byte 3 is the lower 8 bits of the
data to be written or read, creating 16-bit data words.
Control packets are sent to the base module over Comport 3. This Comport is a 32-bit
bi-directional interface, so all four control bytes are written and read as one word.