External Memory Interface Handbook Volume 3: Reference Material

ID 683841
Date 7/24/2019
Public
Document Table of Contents

2.17.3.2. AFI Address and Command Signals

The address and command signals for AFI 4.0 encode read/write/configuration commands to send to the memory device. The address and command signals are single-data rate signals.
Table 32.  Address and Command Signals 

Signal Name

Direction

Width

Description

afi_addr

Input

AFI_ADDR_WIDTH

Address or CA bus (LPDDR3 only). ADDR_RATE_RATIO is 2 for LPDDR3 CA bus.

afi_bg

Input

AFI_BANKGROUP_WIDTH

Bank group (DDR4 only).

afi_ba

Input

AFI_BANKADDR_WIDTH

Bank address. (Not applicable for LPDDR3.)

afi_cke

Input

AFI_CLK_EN_WIDTH

Clock enable.

afi_cs_n

Input

AFI_CS_WIDTH

Chip select signal. (The number of chip selects may not match the number of ranks; for example, RDIMMs and LRDIMMs require a minimum of 2 chip select signals for both single-rank and dual-rank configurations. Consult your memory device data sheet for information about chip select signal width.) (Matches the number of ranks for LPDDR3.)

afi_ras_n

Input

AFI_CONTROL_WIDTH

RAS# (for DDR2 and DDR3 memory devices.)

afi_we_n

Input

AFI_CONTROL_WIDTH

WE# (for DDR2, DDR3, and RLDRAM II memory devices.)

afi_rw_n

Input

AFI_CONTROL_WIDTH * 2

RWA/B# (QDR-IV).

afi_cas_n

Input

AFI_CONTROL_WIDTH

CAS# (for DDR2 and DDR3 memory devices.)

afi_act_n

Input

AFI_CONTROL_WIDTH

ACT# (DDR4).

afi_ref_n

Input

AFI_CONTROL_WIDTH

REF# (for RLDRAM II memory devices.)

afi_rst_n

Input

AFI_CONTROL_WIDTH

RESET# (for DDR3 and DDR4 memory devices.)

afi_odt

Input

AFI_CLK_EN_WIDTH

On-die termination signal for DDR2, DDR3, and LPDDR3 memory devices. (Do not confuse this memory device signal with the FPGA’s internal on-chip termination signal.)

afi_par

Input

AFI_CS_WIDTH

Address and command parity input. (DDR4)

Address parity input. (QDR-IV)

afi_ainv

Input

AFI_CONTROL_WIDTH

Address inversion. (QDR-IV)

afi_mem_clk_disable

Input

AFI_CLK_PAIR_COUNT

When this signal is asserted, mem_clk and mem_clk_n are disabled. This signal is used in low-power mode.

afi_wps_n

Output

AFI_CS_WIDTH

WPS (for QDR II/II+ memory devices.)

afi_rps_n

Output

AFI_CS_WIDTH

RPS (for QDR II/II+ memory devices.)

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