Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1
429
UG586 November 30, 2016
Chapter 3:
RLDRAM II and RLDRAM 3 Memory Interface Solutions
Interfacing with the Core through the Client Interface
The width of certain client interface signals is dependent on the system clock frequency and
the burst length. This allows the client to send multiple commands per FPGA logic clock
cycle as might be required for certain configurations.
shows the
user_cmd
signal and how it is made up of multiple commands
depending on the configuration.
As shown in
, four command slots are present in a single user interface clock
cycle for BL2. Similarly, two command slots are present in a single user interface clock cycle
for BL4. These command slots are serviced sequentially and the return data for read
commands are presented at the user interface in the same sequence. Note that the read
data might not be available in the same slot as that of its read command. The slot of a read
data is determined by the timing requirements of the controller and its command slot. One
such example is mentioned in the following BL2 design configuration.
Assume that the following set of commands is presented at the user interface for a given
user interface cycle.
It is not guaranteed that the read data appears in {DATA0, NOP, DATA1, NOP} order. It might
also appear in {NOP, DATA0, NOP, DATA1} or {NOP, NOP, DATA0, DATA1} etc. orders. In any
case, the sequence of the commands are maintained.
The client interface protocol is shown in
for the RLDRAM II four-word burst
architecture.
X-Ref Target - Figure 3-39
Figure 3-39:
Multiple Commands for user_cmd Signal
Table 3-10:
Command Set in User Interface Cycle
Slots
Commands
0
RD0
1
NOP
2
RD1
3
NOP
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