Visible to Intel only — GUID: nik1410564893772
Ixiasoft
Visible to Intel only — GUID: nik1410564893772
Ixiasoft
4.2. Reset, Status, and Link Training Signals
Refer to Reset and Clocks for more information about the reset sequence and a block diagram of the reset logic.
Signal |
Direction |
Description |
---|---|---|
npor | Input |
Active low reset signal. In the Intel hardware example designs, npor is the OR of pin_perst and local_rstn coming from the software Application Layer. If you do not drive a soft reset signal from the Application Layer, this signal must be derived from pin_perst. You cannot disable this signal. Resets the entire IP Core and transceiver. Asynchronous. In systems that use the hard reset controller, this signal is edge, not level sensitive; consequently, you cannot use a low value on this signal to hold custom logic in reset. For more information about the hard and soft reset controllers, refer to Reset. |
clr_st | Output | This optional reset signal has the same effect as reset_status. You enable this signal by turning On the Enable Avalon-ST reset output port in the parameter editor. |
reset_status | Output |
Active high reset status signal. When asserted, this signal indicates that the Hard IP clock is in reset. The reset_status signal is synchronous to the pld_clk clock and is deasserted only when the npor is deasserted and the Hard IP for PCI Express is not in reset (reset_status_hip = 0). You should use reset_status to drive the reset of your application. This reset is used for the Hard IP for PCI Express IP Core with the Avalon-ST interface. |
pin_perst | Input |
Active low reset from the PCIe reset pin of the device. pin_perst resets the datapath and control registers. This signal is required for Configuration over PCI Express (CvP). For more information about CvP refer to Configuration over PCI Express (CvP). Cyclone V have 1 or 2 instances of the Hard IP for PCI Express. Each instance has its own pin_perst signal. You must connect the pin_perst of each Hard IP instance to the corresponding nPERST pin of the device. These pins have the following locations:
For example, if you are using the Hard IP instance in the bottom left corner of the device, you must connect pin_perst to nPERSL1. For maximum use of the Cyclone® V device, Intel recommends that you use the bottom left Hard IP first. This is the only location that supports CvP over a PCIe link. Refer to the appropriate device pinout for correct pin assignment for more detailed information about these pins. The PCI Express Card Electromechanical Specification 2.0 specifies this pin requires 3.3 V. You can drive this 3.3V signal to the nPERST* even if the VVCCPGM of the bank is not 3.3V if the following 2 conditions are met:
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The following figure illustrates the timing relationship between npor and the LTSSM L0 state.
Signal |
Direction |
Description |
---|---|---|
serdes_pll_locked | Output |
When asserted, indicates that the PLL that generates the coreclkout_hip clock signal is locked. In pipe simulation mode this signal is always asserted. |
pld_core_ready | Input |
When asserted, indicates that the Application Layer is ready for operation and is providing a stable clock to the pld_clk input. If the coreclkout_hip Hard IP output clock is sourcing the pld_clk Hard IP input, this input can be connected to the serdes_pll_locked output. |
pld_clk_inuse | Output |
When asserted, indicates that the Hard IP Transaction Layer is using the pld_clk as its clock and is ready for operation with the Application Layer. For reliable operation, hold the Application Layer in reset until pld_clk_inuse is asserted. |
dlup | Output |
When asserted, indicates that the Hard IP block is in the Data Link Control and Management State Machine (DLCMSM) DL_Up state. |
dlup_exit | Output |
This signal is asserted low for one pld_clk cycle when the IP core exits the DLCMSM DL_Up state, indicating that the Data Link Layer has lost communication with the other end of the PCIe link and left the Up state. When this pulse is asserted, the Application Layer should generate an internal reset signal that is asserted for at least 32 cycles. |
ev128ns | Output |
Asserted every 128 ns to create a time base aligned activity. |
ev1us | Output |
Asserted every 1µs to create a time base aligned activity. |
hotrst_exit | Output |
Hot reset exit. This signal is asserted for 1 clock cycle when the LTSSM exits the hot reset state. This signal should cause the Application Layer to be reset. This signal is active low. When this pulse is asserted, the Application Layer should generate an internal reset signal that is asserted for at least 32 cycles. |
l2_exit | Output |
L2 exit. This signal is active low and otherwise remains high. It is asserted for one cycle (changing value from 1 to 0 and back to 1) after the LTSSM transitions from l2.idle to detect. When this pulse is asserted, the Application Layer should generate an internal reset signal that is asserted for at least 32 cycles. |
lane_act[3:0] |
Output |
Lane Active Mode: This signal indicates the number of lanes that configured during link training. The following encodings are defined:
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currentspeed[1:0] | Output |
Indicates the current speed of the PCIe link. The following encodings are defined:
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ltssmstate[4:0] | Output |
LTSSM state: The LTSSM state machine encoding defines the following states:
|