Interfaces
Internal (core) Interface
The internal interface to the PHY/DDR controller, which is implemented in the core fabric, contains the
following interface signals as listed below in table 1.
Signal Name
Direction
Description
clk 1 Input
Driven by user. Clock signal. This is the reference clock
coming in from the board.
ddr_int_clk_div2 1 Output
In 2X Clock mode the clock from PHY will be at half the
controller clock which should be used to send and receive data
ddr_int_clk_div4 1 Output
When the wide bus interface is enabled, the clock from PHY
will be at one quarter the controller clock which should be
used to send and receive data from core to controller
Driven by user. Reset to PHY. Asserted active low.
Driven by user. Reset to DDR controller. Asserted active low.
ddr_int_busy 1 Output
Indicates that the DDR3 Controller is busy and is not accepting
new requests.
ddr_int_busy_align 1 Output
When the wide bus interface is enabled and in 2X clock mode,
indicates that the DDR3 Controller is busy and is not accepting
new requests.
Address bus containing row, column, and bank information.
ddr_int_burst_size 8 Input
Indicates burst size of given read/write request.
Valid ranges of this value are:
8’d252 (multiples of 4) for DDR3
ddr_int_wrdata_req 9 Output
Request by DDR Controller for data to be written to the DDR
Memory. This is asserted some number of clock cycles after a
write request, and is burst length number of clock cycles in
length per write request.
ddr_int_wrdata_req_early 9 Output
Early request by DDR controller for data to be written to the
DDR memory. Signal will be asserted earlier then
‘ddr_int_wrdata_req’ which can be used.
ddr_int_wrdata_req_align 9 Output
When the wide bus interface is enabled and in 2X Clock mode,
request by DDR Controller for data to be written to the DDR
Memory. This signal bus essentially performs a single
alignment function but is provided as a multi-bit signal for
ddr_int_wrdata_req_early_align 9 Output
When the wide bus interface is enabled and in 2X Clock mode,
early request by DDR Controller for data to be written to the
DDR Memory. Signal will be asserted earlier then
‘ddr_int_wrdata_req_align’ which can be used. This signal bus
essentially performs a single alignment function but is
provided as a multi-bit signal for timing purposes.
ddr_int_wrdata
[SIZE*4-
1:0]
Input
Data to be written to the DDR Memory. This data is provided
two cycles after ddr_int_wrdata_req is asserted. SIZE: 72, 64,
32, 16, 8. When the wide bus interface is enabled, the SIZE
parameters and consequently the bus width, are doubled.
ddr_int_wrdata_mask
[SIZE/2-
1:0]
Input
Data mask corresponding to “ddr_int_wrdata”. When any
data mask bit is asserted, the data contained in the
corresponding ‘ddr_int_wrdata’ byte will not be written to
Memory. SIZE: 72, 64, 32, 16, 8. When the wide bus interface is
UG031, Nov 18, 2014
9
(20 paginas)
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