ADM-XRC SDK 2.8.1 User Guide (Linux)
© Copyright 2001-2009 Alpha Data
The memif_ddrsdram_pinout_t datatype is exported by the memif package, and is used to specify the physical configuration of an instance of ddrsdram_port.
It is a record type, defined as follows:
type ddrsdram_pinout_t is record family : family_t; flight_time : natural; dqs_dq_delay : boolean; dqs_dm_delay : boolean; ck_width : natural; cke_width : natural; num_phys_bank : natural; num_bank_bits : natural; num_addr_bits : natural; end record;
This datatype can normally treated as an abstract datatype, since the user application need typically only use one of the predefined constants of type ddrsdram_pinout_t. However, should it be necessary to create a new value, the members are defined as follows:
Member | Type | Function |
family | family_t | Specifies the FPGA family that the memory port targets. |
flight_time | natural | Round trip DQ delay in 1/4 clock cycles. |
dqs_dq_delay | boolean | If true, specifies that DQS PCB traces have additional delay with respect to DQ PCB traces. |
dqs_dm_delay | boolean | If true, specifies that DQS PCB traces have additional delay with respect to DM PCB traces. |
ck_width | natural | Number of CK / CK# pairs present in the rc bus. |
cke_width | natural | Number of CKE# pins present in the rc bus. |
num_phys_bank | natural | Specifies the number of physical banks being driven by the memory port, which is also the number CS# pins present in the rc bus. |
num_bank_bits | natural | Specifies the number of BA bits (internal bank bits) on the devices being driven by the memory port. |
num_addr_bits | natural | Specifies the number of A bits (row / column address bank bits) on the devices being driven by the memory port. |
The value of ddrsdram_pinout_t passed in the pinout parameter of a ddrsdram_port determines the proper values to pass for the ra_width and rc_width parameters. The relevant formulae are:
ra_width = num_bank_bits + num_addr_bits
rc_width = 2 * (rd_width / 8) + 2 * num_ck + cke_width + num_phys_bank + 3