New ContributorFPGA- SDC creation for 0.00039MHz clk
I have to create the sdc description for 0.00039MHz which was generated using counter logic.
FPGA_CLK is 26 MHz, from that i would like to specify the clk value in my sdc file
i am trying to give this clk using the below command:
create_generated_clock -divide_by 65536 -source [get_ports FPGA_CLK] -name Clkprescaler:Clockprescaler|divider[15] [get_registers {Clkprescaler:Clockprescaler|divider[15]}]
But it is not taken by the tool, its still showing the error as unconstrainted.
any suggestions?
Re
Instead of using a slow clock for your sensor detection module, you update it only when clk_en is high:
always @(posedge clk or negedge reset_n) begin
if (!reset_n) begin
sensor_state <= 0;
end else if (clk_en) begin
sensor_state <= sensor_input; // Sample the sensor input at 390 Hz
end
end
If you need to detect a rising edge of the sensor input, you can do:
reg sensor_prev; always @(posedge clk or negedge reset_n) begin if (!reset_n) begin sensor_prev <= 0; end else if (clk_en) begin sensor_prev <= sensor_input; end end wire sensor_rising_edge = clk_en & sensor_input & ~sensor_prev;
This will trigger a pulse only when the sensor input rises at 390 Hz.
