Sundance SMT317 - Manual (Page 10)

Version 6.1 Page 10 of 24 SMT317 User Manual
8. SDB
The SMT317 provides one Sundance Digital Bus (SDB). This 16-bit data parallel link
for synchronous transmission can achieve high-speed data transfer across 40-way
flat ribbon cables with ground-interlaced 3.3v signals (Ref. SMT3xx-SDB-CAB).
The SDB is connected directly to the Virtex device. The SDB implementation on this
module operates as an
output only .
The user defined pins (UD0, UD1) are not used. The write enable pin (WEN) is driven
active (low) by the SMT317 when it is transmitting data on the SDB. The SDB drives
at LVTTL levels. The SDB pinout is described in
Table 4.
The SDB interface present in the SMT317 implements a flow control meaning that
when the receiver on the other end stops receiving, the data is not overwritten but
pills up in the SMT317’s own FIFO until it is full. Only then data is overwritten.
The SDB interface provides a 511 position FIFO. Each position is 32-bit wide.
The 16-bit SDB interface only transfers multiples of 32-bit words.
Only one transfer speed is available on the SMT317 SDB released after 01/09/2005.
The clock speed is 50 MHz.
You should refer to SDB specifications V2.0 and above for technical information.
9. Data formatting
The sampled data is output on the SDB (Sundance Digital Bus) connector.
The physical link presents ADC samples one at a time (16-bit wide) but the SMT317
packets ADC data samples by pairs and sends multiples of 2 x 16-bit packets with
the least significant bit being sent on D0.
The channels are paired in the following manner:
Ch0, Ch4,
Ch1, Ch5,
Ch2, Ch6,
Ch3, Ch7.