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led_blinker: Decrease blink speed to 15 Hz 

15 Hz is more obviously "blinky" than 30 Hz (at least at 50% duty cycle).

Signed-off-by: Sean Anderson <seanga2@gmail.com>
This commit is contained in:
Sean Anderson 2023-03-15 14:06:04 -04:00
parent 01f9d96173
commit 508b090983
2 changed files with 7 additions and 7 deletions
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2
examples/led/README.adoc
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@ -2,7 +2,7 @@
This directory contains an example design to test the LED blinkers. It runs on an This directory contains an example design to test the LED blinkers. It runs on an
https://www.olimex.com/Products/FPGA/iCE40/iCE40HX8K-EVB/[Olimex iCE40HX8K-EVB]. https://www.olimex.com/Products/FPGA/iCE40/iCE40HX8K-EVB/[Olimex iCE40HX8K-EVB].
Pushing the buttons will cause the LEDs to blink at 30 Hz. Pushing the buttons will cause the LEDs to blink at 15 Hz.
To compile this design, run To compile this design, run

12
rtl/led_blinker.v
View File

@ -22,17 +22,17 @@ module led_blinker (
parameter LEDS = 2; parameter LEDS = 2;
/* /*
* $ scripts/lfsr.py 0x140000 0x1fffff 16 * $ scripts/lfsr.py 0x300000 4166667 16
* *
* 16.78 ms * 33.33 ms
*/ */
localparam TIMER_RESET = 21'h1ffffe; localparam TIMER_RESET = 22'h27b194;
/* 16 cycles */ /* 16 cycles */
localparam TEST_TIMER_RESET = 21'h13333f; localparam TEST_TIMER_RESET = 22'h15557f;
reg active, active_next; reg active, active_next;
reg [LEDS - 1:0] out_next, triggered, triggered_next; reg [LEDS - 1:0] out_next, triggered, triggered_next;
reg [20:0] lfsr, lfsr_next; reg [21:0] lfsr, lfsr_next;
initial begin initial begin
active = 0; active = 0;
@ -45,7 +45,7 @@ module led_blinker (
active_next = active; active_next = active;
triggered_next = triggered | triggers; triggered_next = triggered | triggers;
out_next = out; out_next = out;
lfsr_next = { lfsr[19:0], lfsr[20] ^ lfsr[18] }; lfsr_next = { lfsr[20:0], lfsr[21] ^ lfsr[20] };
if (&lfsr) begin if (&lfsr) begin
if (active) begin if (active) begin
active_next = 0; active_next = 0;