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SegmentationFault's avatar
SegmentationFault
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5 years ago

Strange behaviour with LEDs, 1 means LED off and 0 means LED on

Hello, I have a development board with an EP4CE6E22C8 FPGA. I have the following verilog code in Quartus Prime: module Test(out); output [7:0] out; assign out = 8'b00111100; endmodule ...
FPGA56's avatar
FPGA56
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5 years ago

This is generally due to the hardware setup, with 3.3V connected to the LED which leads to the pin (see the image attached).

When the pin goes low, current flows through the LED towards the pin. When the pin is high both sides of the LED are at 3.3V and thus no current flows.