Visible to Intel only — GUID: qet1599630793434
Ixiasoft
Visible to Intel only — GUID: qet1599630793434
Ixiasoft
2.2.3.3. Input Path
The input path of the IP consists of a data path, a strobe path, and a read enable path as shown in the following figure.
Path | Description |
---|---|
Data Path | Receives data from external device to the FPGA core logic.
The data path consists of a PVT compensated delay chain, a DDIO and a read FIFO.
Signals used in this path are:
The IP supports SDR input by sending data on single clock cycle from the external device. |
Strobe Path | Input strobe (dqs) to capture input data from external device.
The strobe path consists of pstamble_reg (a gating component) and a PVT compensated delay chain.
Signals used in this path are:
|
Read and Strobe Enable Path | Generates control signals for strobe calibration and reading data from Read FIFO.
The read and strobe enable path consists of VFIFO, DQS_EN FIFO, and an interpolator.
Signals used in this path are:
|
Read Operation Sequence Number | Operation |
---|---|
1 | The core asserts the rdata_en signal to the PHY Lite for Parallel Interfaces IP and issues a read command to the external device. |
2 | VFIFO and DQS_EN FIFO generate the dqs_enable signal to pstamble_reg. This signal is delayed by the programmed read latency (which should match the latency of the external device). |
3 | The pstamble_reg generates dqs_clean signal as valid data enters the read path. |
4 | The Delay Chain (PVT) adjusts the strobe with phase offset between the strobe and the input data (for example, 90° phase shift for DDR center-alignment). |
5 | The dqs signal is then used as strobe to read data from external device into the DDIO and Read FIFO modules. |
6 | The VFIFO asserts the read_enable signal to Read FIFO and the rdata_valid signal to the core simultaneously. The PHY Lite for Parallel Interfaces IP sends the captured data to the core with the associated valid signal. |
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