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// Simple tri-colour LED blink example, with button control
//
// Green LED blinks forever. Blue LED turned on when Button 5 is pressed.
// Red LED turned on when Button 6 is pressed.
//
// LOG2DELAY controls the division of the module clock to the bit interval
// (by requiring count to 2 ** LOG2DELAY before changing LED state bits)
//
// On EVT Fomu boards:
//
// 1st LED colour - Blue - controlled by pressing Button 5, or connect 1 to 2
// 2nd LED colour - Red - controlled by pressing Button 6, or connect 3 to 4
// 3rd LED colour - Green - controlled by clock (blinking)
//
// On DVT / Hacker / Production Fomu boards:
//
// 1st LED colour - Blue - turn on by connecting pin 1 to pin 2
// 2nd LED colour - Green - controlled by clock (blinking)
// 3rd LED colour - Red - turn on by connecting pin 3 to pin 4
//
// We use `defines to handle these two cases, because the SB_RGBA_DRV
// iCE40UP5K hard macro is unable to do RGBn to output pin mapping internally
// (the RGB0 / RGB1 / RGB2 parameters to SB_RGBA_DRV *must* be mapped
// to the same named RGB0 / RGB1 / RGB2 physical pins; arachne-pnr
// errors if they are not, and currently nextpnr just ignores mismapped
// pins and enforces this mapping)
//
// This is all kludged into a single file to make a standalone simple test;
// a better design would wrap SB_RGBA_DRV into a Fomu specific module and
// hide the LED colour mapping; and also set the appropriate pins for
// the buttons at instantiation time.
//
`ifdef EVT
`define BLUEPWM RGB0PWM
`define REDPWM RGB1PWM
`define GREENPWM RGB2PWM
`else
`ifdef PVT
`define GREENPWM RGB0PWM
`define REDPWM RGB1PWM
`define BLUEPWM RGB2PWM
`elsif HACKER
`define BLUEPWM RGB0PWM
`define GREENPWM RGB1PWM
`define REDPWM RGB2PWM
`else
`error_board_not_supported
`endif
`endif
module blink_blue (
output rgb0, // SB_RGBA_DRV external pins
output rgb1,
output rgb2,
output usb_dp,
output usb_dn,
output usb_dp_pu,
input clki // Clock
);
// Assign USB pins to "0" so as to disconnect Fomu from
// the host system. Otherwise it would try to talk to
// us over USB, which wouldn't work since we have no stack.
assign usb_dp = 1'b0;
assign usb_dn = 1'b0;
assign usb_dp_pu = 1'b0;
// Connect to system clock (with buffering)
wire clkosc;
SB_GB clk_gb (
.USER_SIGNAL_TO_GLOBAL_BUFFER(clki),
.GLOBAL_BUFFER_OUTPUT(clkosc)
);
assign clk = clkosc;
// Use counter logic to divide system clock. The clock is 48 MHz,
// so we divide it down by 2^28.
reg [28:0] counter = 0;
always @(posedge clk) begin
counter <= counter + 1;
end
// Instantiate iCE40 LED driver hard logic, connecting up
// latched button state, counter state, and LEDs.
//
// Note that it's possible to drive the LEDs directly,
// however that is not current-limited and results in
// overvolting the red LED.
SB_RGBA_DRV #(
.CURRENT_MODE("0b1"), // half current
.RGB0_CURRENT("0b000011"), // 4 mA
.RGB1_CURRENT("0b000011"), // 4 mA
.RGB2_CURRENT("0b000011") // 4 mA
) RGBA_DRIVER (
.CURREN(1'b1),
.RGBLEDEN(1'b1),
.`BLUEPWM(counter[26]), // Blue
.RGB0(rgb0),
.RGB1(rgb1),
.RGB2(rgb2)
);
// For more information see the iCE40 UltraPlus LED Driver Usage Guide, pages 19-20
//
// https://www.latticesemi.com/-/media/LatticeSemi/Documents/ApplicationNotes/IK/ICE40LEDDriverUsageGuide.ashx?document_id=50668
endmodule
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