FPGA, SoC, And CPLD Boards And Kits
FPGA Evaluation and Development Kits
Announcements
Intel Support hours are Monday-Fridays, 8am-5pm PST, except Holidays. Thanks to our community members who provide support during our down time or before we get to your questions. We appreciate you!

Need Forum Guidance? Click here
Search our FPGA Knowledge Articles here.
5232 Discussions

and gate acting as or and vysa versa

rvais1
Beginner
391 Views

hey

I'm new to altera fpga , I've bought development board based on EP4CE6E22 cyclon IV and tryed to program it with basic program in quartus environment

 

module my_and(a,b,c); input a,b; output c; assign c = a & b; endmodule

I've loaded pin assignment from files that came with the board and programmed it with some chinese jtag blaster.

 

but when i tryed to push one or the other or both (attached to a,b signals)button - the led turned on , and went off when released (like OR GATE)

 

so i tryed to program it as OR GATE gate and the board started acting like AND GATE

 

am i doing somthing wrong?

 

0 Kudos
1 Solution
ak6dn
Valued Contributor III
108 Views

Check the logic sense of your switches and LED pins. You are assuming PUSHed=1 and not=0, and out=1 for LED on, and out=0 for LED off.

 

On many/most all boards pushbuttons will be connected to a pin with a pullup, so the default input will be a '1' (high). When you push it it goes to a '0' (low).

 

The LED could be driven either active high ('1' high for ON, '0' low for OFF) or active low ('1' high for OFF, '0' low for ON). Check the schematic/docs for which way on your board.

View solution in original post

1 Reply
ak6dn
Valued Contributor III
109 Views

Check the logic sense of your switches and LED pins. You are assuming PUSHed=1 and not=0, and out=1 for LED on, and out=0 for LED off.

 

On many/most all boards pushbuttons will be connected to a pin with a pullup, so the default input will be a '1' (high). When you push it it goes to a '0' (low).

 

The LED could be driven either active high ('1' high for ON, '0' low for OFF) or active low ('1' high for OFF, '0' low for ON). Check the schematic/docs for which way on your board.

Reply