3.2. JESD204C Design Example Clock and Reset
Clock Signal | Direction | Description |
---|---|---|
mgmt_clk | Input | LVDS differential clock with frequency of 100 MHz. |
refclk_xcvr | Input | Transceiver reference clock with frequency of data rate/ factor of 33. |
refclk_core | Input | Core reference clock with the same frequency as refclk_xcvr. |
in_sysref | Input | SYSREF signal. Maximum SYSREF frequency is data rate/(66x32xE). |
sysref_out | Output | |
txlink_clk rxlink_clk |
Internal | TX and RX link clock with frequency of data rate/132. |
txframe_clk rxframe_clk |
Internal |
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tx_fclk rx_fclk |
Internal |
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spi_SCLK | Output | SPI baud rate clock with frequency of 20 MHz |
When you load the design example into an FPGA device, an internal ninit_done event ensures that the JTAG to Avalon Master bridge is in reset as well as all the other blocks.
The SYSREF generator has its independent reset to inject intentional asynchronous relationship for the txlink_clk and rxlink_clk clocks. This method is more comprehensive in emulating the SYSREF signal from an external clock chip.
Reset Signal | Direction | Description |
---|---|---|
global_rst_n | Input | Push button global reset for all blocks, except the JTAG to Avalon® Master bridge. |
ninit_done | Internal | Output from Reset Release IP for the JTAG to Avalon® Master bridge. |
mgmt_rst_in_n | Internal | Reset for Avalon® memory-mapped interfaces of various IPs and inputs of reset sequencers:
The global_rst_n, hw_rst, or edctl_rst_n port asserts reset on mgmt_rst_in_n. |
j20c_tx_avs_rst_n j20c_tx_avs_rst_n |
Internal | Reset the JESD204C TX and RX IP Avalon® memory-mapped interfaces through the reset sequencer 0 reset_out0 port. These interfaces are reset when mgmt_rst_in_n reset is asserted. |
edctl_rst_n | Internal | The ED Control block is reset by JTAG to Avalon® Master bridge. The hw_rst and global_rst_n ports do not reset the ED Control block. |
sysref_rst_n | Internal | Reset for SYSREF generator block in the ED Control block using the reset sequencer 0 reset_out2 port. The reset sequencer 0 reset_out2 port deasserts the reset if the core PLL is locked. |
j204c_tx_phy_rst_n j204c_rx_phy_rst_n |
Internal | Reset transceiver PHY in the JESD204C IP by asserting mgmt_rst_in_n.
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core_pll_rst | Internal | Resets the core PLL through the reset sequencer 0 reset_out0 port. The core PLL resets when mgmt_rst_in_n reset is asserted. |
j204c_tx_rst_n j204c_rx_rst_n |
Internal | Resets the JESD204C link and transport layers in txlink_clk, rxlink_clk, txframe_clk, and rxframe_clk domains.
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hw_rst | Internal | Assert and deassert hw_rst by writing to the rst_ctl register of the ED Control block. mgmt_rst_in_n asserts when hw_rst is asserted. |