binary to hex decoder?

[pocketroxetz]

Does anyone know how to draw a schematic for a 7 bit binary to 8 bit hexadecimal (2 bit hex) decoder using standard logic gates like muxes, decoders etc.? I can't really think of anything except using adders to add the first 3 bits and the last 4 bits. Any ideas? Thx.

 

[Peter]

Er, in circuitry, everything is binary and stays binary. Do you want to decode onto a 7-segment display or what?

 

[pocketroxetz]

Yes, it's going to input from 7 input switches and output on the 2 LED's on the 7-seg display.

 

[Peter]

There are plenty of 74something standard chips that do it for you.

Otherwise, put up one logic equation each from your seven input bits onto a True or False for each of the 14 LED segments, reduce the equations using bool math, and then build it from standard gates. That then isn't Highly Technical anymore.

(Hint: There is an obvious simplification. You don't need all seven inputs for each of the LED segments.)

 

[LavidDichterman]

make a truth table and convert it to a karnaugh map, get the sum of products / product of sums from that and build it with standard logic. that'll probably be faster than looking for something. if you want to copy a design, follow peter's advice and look up the white pages to the appropriate 74xxx chip

 

[itachi]

74ls47 i believe is the bcd to 7-segment decoder..
no.. dont minimize using kmaps. qm minimization works best for functions with multiple outputs.

 

[Varun]

Yes it is the 7447 that is the BCD to 7 Segment decoder.

Have fun!

 

[MAW1082]

If you're doing this through the use of a cpu its easy. You can just use a table to correlate the hexadecimal value to the output code on 7 output pins.

example:

if you want to find the output code of e

1. load the index of the table.
2. add value to the index.
3. retrieve value in indexed address.
4. output to port.

assuming the first value on your table is for 0, second for 1, and so on . . .