7 segment decimal point display??

[brain8]

using a BCD to seven segment converter how do i access the decimal point on the led display? i am using Xilinx schematic editor to create a display unit with a BCD - 7 segment converter and i need to display the decimal points at variable points on the displays. I am going to implement it on a Spartan 3 FPGA board.

i need to know hoe to make the DP active using bcd values,etc

 

[blueroomelectronics]

Not sure there are many Xilinx Spartan 3 users here.

 

[pc88]

using a BCD to seven segment converter how do i access the decimal point on the led display? i am using Xilinx schematic editor to create a display unit with a BCD - 7 segment converter and i need to display the decimal points at variable points on the displays. I am going to implement it on a Spartan 3 FPGA board.

i need to know hoe to make the DP active using bcd values,etc

Generally a BCD to 7-segment driver does not have any connections to the DP led. You have to use a separate control line.

 

[brain8]

i know but ....

Generally a BCD to 7-segment driver does not have any connections to the DP led. You have to use a separate control line.

i see but i need to know how i can turn on the decimal point on a seven segment LED using four inputs.i.e 0000 or 0101 or 1111,etc.

 

[mvs sarma]

Generally a BCD to 7-segment driver does not have any connections to the DP led. You have to use a separate control line.

If any mathematical function is performed and if a decimal is to be displayed, it has to output an additional bit beyond BCD code, Only then perhaps, you could drive the dp.

 

[saturn1bguy]

i see but i need to know how i can turn on the decimal point on a seven segment LED using four inputs.i.e 0000 or 0101 or 1111,etc.

The DP on a seven segment-display is just another LED. You need to provide the logic needed to decode it, and then drive it with something that can source 7-20mA, depending on how bright you want it. Some people use transistors, some use buffer/gates.

Perhaps you're asking how to decode it? Usually with additional combinatorial logic (gates). First you must define the conditions when you want it on, and then distill this to gates required by using truth tables/K-maps, etc. I presume since you're using FPGAs you already know how to do this.

 

[brain8]

thx...

thanks for your help. i thougth about it and i'll just turn on the decimal point using a pin on the FPGA by sending the correct logic signal using gates. but i also need to know how i can display characters (in particular A,C,V) using the BCD to 7 segment decoder?

any suggesstions???

 

[saturn1bguy]

I also need to know how i can display characters (in particular A,C,V) using the BCD to 7 segment decoder?

You need to modify your seven-segment decoder to include more than just BCD digits, right, unless of course you want A, C, and V to be displayed for some number(s) between zero and nine.

Which means you need to design a BINARY to seven-segment decoder to allow more states than just ten, and then define which number(s) between 10 and 15 will represent those letters...

 

[Boncuk]

thanks for your help. i thougth about it and i'll just turn on the decimal point using a pin on the FPGA by sending the correct logic signal using gates. but i also need to know how i can display characters (in particular A,C,V) using the BCD to 7 segment decoder?

any suggesstions???

An FPGA has lots of I/O-pins. If you program it accordingly you will have an output for each decimal point to control.

To display characters you have two choices: alphanumeric display (16 segments including DP) or 5X7 LED matrix display. A BCD-decoder doesn't offer more than 7 segments to control.

 

[kchriste]

but i also need to know how i can display characters (in particular A,C,V) using the BCD to 7 segment decoder?

Drive the 7 segment (including the dp) with the FPGA via an 8bit buffer chip. Put the 0-9 digit decode lookup in the FPGA along with any other characters you wish to display. As noted by Boncuk, for alpha characters, there are better display types other than seven segment. A V would look like a U on a seven segment display and Bs look like 8s or 6s.

 

[mvs sarma]

thanks for your help. i thougth about it and i'll just turn on the decimal point using a pin on the FPGA by sending the correct logic signal using gates. but i also need to know how i can display characters (in particular A,C,V) using the BCD to 7 segment decoder?

any suggesstions???

Instead, you could prefer 16*2 LCD module or choose alphanumeric LED displays.