1.1.1. Estimating Pin Requirements
- Find out how many read data pins are associated per read data strobe or clock pair, to determine which column of the DQS and DQ group availability (×4, ×8/×9, ×16/×18, or ×32/×36) refer to the pin table.
- Check the device density and package offering information to see if you can implement the interface in one I/O bank or on one side or on two adjacent sides.
Note: If you target Arria II GX devices and you do not have enough I/O pins to have the memory interface on one side of the device, you may place them on the other side of the device. Arria II GX devices allow a memory interface to span across the top and bottom, or left and right sides of the device. For any interface that spans across two different sides, use the wraparound interface performance.
- Calculate the number of other memory interface pins needed, including any other clocks (write clock or memory system clock), address, command, RUP, RDN, RZQ, and any other pins to be connected to the memory components. Ensure you have enough pins to implement the interface in one I/O bank or one side or on two adjacent sides.
- The DQS groups in Arria II GX devices reside on I/O modules, each consisting of 16 I/O pins. You can only use a maximum of 12 pins per I/O modules when the pins are used as DQS or DQ pins or HSTL/SSTL output or HSTL/SSTL bidirectional pins. When counting the number of available pins for the rest of your memory interface, ensure you do not count the leftover four pins per I/O modules used for DQS, DQ, address and command pins. The leftover four pins can be used as input pins only.
- Refer to the device pin-out tables and look for the blank space in the relevant DQS group column to identify the four pins that cannot be used in an I/O module for Arria II GX devices.
- If you enable Ping Pong PHY, the IP core exposes two independent Avalon interfaces to user logic, and a single external memory interface of double the width for the data bus and the CS#, CKE, ODT, and CK/CK# signals. The rest remain as if in single interface configuration.
You should test the proposed pin-outs with the rest of your design in the Quartus Prime software (with the correct I/O standard and OCT connections) before finalizing the pin-outs. There can be interactions between modules that are illegal in the Quartus Prime software that you might not know about unless you compile the design and use the Quartus Prime Pin Planner.
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