Hi.I'm trying to drive the on board seven segment display on a Cyclone III development kit board EP3C120. The seven segment display is Lumex LDQ-M2212R1, quad digit. I appreciate any advice ranging from digital design to verilog coding to fpga. I'm picking up all these things in one go. 1. I did a counter to select all 4 digits one after another continuously as the display only has one digit selection at a time. I tried connecting straight from on board 50 MHz clock to clock of my counter design but compiling gave error of minimum pulse width. So I thought maybe I should feed the clock input to a megafunction PLL first then only to the counter. Is this the correct way of doing things? 2. I could drive one digit at a time (without clock) successfully but the digits lit up quite dimly as compared to the minus sign. It has to be relatively darker than a well lit up room for me to see the numbers lighting up. Is this typical of the seven segment display or am I doing something not right? Thanks.
Your 1:4 multiplex method seems basically correct. Typically, a kHz multiplex frequency would be used, generated by a synchronous counter. To achieve equal brightness of the minus sign, the duty cyle must be reduced. Unfortunately, the segment lines are driven from a 1.8V VCCIO without decreasing the current limiting resistors (could be considered a design flaw, to my opinion). Generally, for acceptable brightness, digit drivers with higher current capability than FPGA IOs would be needed.
Thank you FvM.I'm inexperienced from both theory and hands on here. I am doing this seven segment driver for my self tutorials. I've been looking at it for all day and all night because I thought it didn't work. All I was trying to do was to drive all the 4 digits on the display with the same number controlled from the same DIP switches. Until I gave up and switched off the lights to my brightly lit room and saw that the 4 digits were actually displaying what it should but too dim for me to see!!. Dim displays, dim me, what a match! Now that I'm happy to go on, I cannot yet figure out how to feed the input with 4 different sets of codes having just 8 DIP switches. I'm sure there are ways for doing that with just my laptop and fpga board at home without needing external signal generators and ribbon cables? Thanks.
Hello to everybody.I want to use the same display on ciii board. Where can i find the datasheet on it?I've already tried to look at lumex.com, but it is quiet difficult to find it there. or what are the signals: an ca? thnaks a lot
Display seems to be very-very dim.Datasheet on it says that max Forward Voltage is 2.6 V. The usual voltage for him is 1.8 V and if i set for example about 2.5 V?
That's a "design flaw" of this board !Already cost me hours too.... The User 7-Seg is connected to a 1.8V VCCIO IO Bank. No chance to up the voltage to 2.5 V. (Hardwired, see board schematics). Just switch the lights off in the room.... BTW: The Power 7-Seg on the same board is driven by the MAX II, which is configured with enough voltage. So this one is glowing brightly.