3.3. Design Example Clock and Reset
The main reference clocks for the design example are refclk_core and refclk_xcvr. These clocks must be supplied from a single external source (i.e refclk_core and refclk_xcvr must be synchronous to one another). The refclk_core is the reference clock for the core PLL and the refclk_xcvr is the reference clock for the TX/RX transceiver PHY. The core PLL generates the link_clk and frame_clk from refclk_core.
The link_clk clocks the F-Tile JESD204B IP core link layer and link interface of the transport layer. The frame_clk clocks the transport layer, test pattern generator and checker modules, and any downstream modules. An external source supplies a clock called the mgmt_clk to clock the Avalon® memory-mapped interface interfaces of Platform Designer components.
Clock | Description | Source | Modules Clocked |
---|---|---|---|
refclk_core | Reference clock for core PLL | External | Core PLL |
refclk_xcvr | Reference clock for F-tile FGT PMA QUAD and System PLL | External | F-tile FGT PMA QUAD and System PLL |
link_clk | Link layer clock | refclk_core | JESD204B IP core link layer, transport layer link interface |
frame_clk | Frame layer clock | refclk_core | Transport layer, test pattern generator and checker, downstream modules |
mgmt_clk | Control plane clock | External | 100 MHz clock |
spi_SCLK | SPI serial clock | Internal | Driven by the master to slaves, to synchronize the data bits |
sysclk | System PLL clock | External | Hard IP EMIB crossing. Generated from F-Tile System PLL IP |
Signal | Direction | Description |
---|---|---|
global_rst_n | Input | Global reset for all blocks except JTAG-to- Avalon® memory-mapped interface master bridge. Signal is debounced internally in the design example. |
ninit_done | Internal | Output from Intel FPGA Reset Release IP for the JTAG-to- Avalon® memory-mapped interface master bridge. Deassert only when FPGA enter user mode. |
hw_rst | Internal | Active high reset. Reset assertion/deassertion control from bit [30] of PIO control. It asserts mgmt_rst_in_n. |
mgmt_rst_in_n | Internal | Active low reset. Assert when either global_rst_n or hw_rst assert. It reset all Avalon® memory-mapped interface interfaces of various IPs as well as the 2 reset sequencers. |
core_pll_rst | Internal | Active high reset. Reset for Core PLL. It's sequenced via reset sequencer 0. It asserts when mgmt_rst_in_n is asserted. |
jesd204_tx_avs_rst_n | Internal | Active low reset. Reset the IP TX Avalon® memory-mapped interface interface. It's sequenced via reset sequencer 0. It asserts when mgmt_rst_in_n is asserted. |
jesd204_rx_avs_rst_n | Internal | Active low reset. Reset the IP RX Avalon® memory-mapped interface interface. It's sequenced via reset sequencer 1. It asserts when mgmt_rst_in_n is asserted. |
jesd204_tx_rst_n | Internal | Active low reset. Reset the JESD204B TX Link and Tile. It's sequenced via reset sequencer 0. It asserts when mgmt_rst_in_n is asserted. |
jesd204_rx_rst_n | Internal | Active low reset. Reset the JESD204B RX Link and Tile. It's sequenced via reset sequencer 1. It asserts when mgmt_rst_in_n is asserted. |
jesd204_tx_rst_ack_n | Internal | Reset handshakes signal with jesd204_tx_rst_n. |
jesd204_rx_rst_ack_n | Internal | Reset handshakes signal with jesd204_rx_rst_n. |