The table shows the read data signals for a PHY only option.
| Signal | I/O | Description |
|---|---|---|
| rdData[DQ_WIDTH × 8 – 1:0] | O | DRAM read data. Eight bits for each DQ lane on the DRAM bus. This port transfers data for an entire BL8 read on each system clock cycle. rdData is only valid when the rdDataEn, per_rd_done, or rmw_rd_done is asserted. Your design must consume the read data when rdDataEn one of these “data valid” signals asserts. There is no data buffering in the PHY. |
| rdDataEn | O | Read data valid. This signal asserts High to indicate that the
rdData and rdDataAddr signals are valid. rdDataEn asserts High for
one system clock cycle for each BL8 read, unless the read was tagged
as a special type of read. See the optional per_rd_done and rmw_rd_done signals for details on special reads. rdData must be consumed when rdDataEn asserts or data is lost. Active-High. |
| rdDataAddr[DATA_BUF_ADDR_WIDTH – 1:0] | O | Optional control signal. PHY stores and returns a data buffer address for each in-flight read CAS command. The rdDataAddr signal returns the stored addresses. It is only valid when the PHY asserts rdDataEn, per_rd_done, or rmw_rd_done. Your design can use this signal to manage the process of capturing and storing read data provided by the PHY, but this is completely optional. |
| per_rd_done | O | Optional read data valid signal. This signal indicates that a
special type of read has completed and its associated rdData and
rdDataAddr signals are valid. When PHY input winInjTxn is asserted High at the same time as mcRdCAS, the read is tagged as a special type of read, and per_rd_done asserts instead of rdDataEn when data is returned. |
| rmw_rd_done | O | Optional read data valid signal. This signal indicates that a
special type of read has completed and its associated rdData and
rdDataAddr signals are valid. When PHY input winRmw is asserted High at the same time as mcRdCAS, the read is tagged as a special type of read, and rmw_rd_done asserts instead of rdDataEn when data is returned. |
| rdDataEnd | O | Unused. Tied High. |