Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

digital electronics help !!!

Status
Not open for further replies.

thegreatleo2003

New Member
hi ppl im having trouble figuring out the digital electronics prob

design a combination circuit that gives output 0 when any of the inputs 1,2,3,4,5 are high and gives output 8 when any of inputs 6,7,8,9 are high and show result display on 7 seg

like
when 1 is set high output is 0
when 2 is set high output still remains 0

so my guess is that it uses a decimal to bcd encoder i have done the part when
6 or 7 or 8 or 9 is set high output is 8
and its expression is like

A3=6+7+8+9
A0-A2=remains zero as i only need two outputs i.e 0 and 8
(1 to 9 are the decimal lines)

im building the encoder using OR gates but how do i implement the "outputs zero when inputs are high for 1 2 3 4 5" ???
 
The 6 segments for 0 are always on, and the - segment (that converts 0 to 8) comes on when 6-9 are high.
So you just need a single 4-input OR gate that links 6-9 directly to the - segment, and the circuit effectively ignores inputs 1-5.

However, you haven't said what should happen when (a) all inputs are low and (b) when some of 1-5 and some of 6-9 are high.
 
You could use a truth table, with all your inputs and the possible output. The inputs are 4 bits and your output is also 4 bits because the maximum output is 8 (1000). The table is as follows:

---------------------------------
inputs | output |
---------------------------------
Q3 Q2 Q1 Q0 | I1 I2 I3 I4 |
0 0 0 1 | 0 0 0 0 |
0 0 1 0 | 0 0 0 0 |
0 0 1 1 | 0 0 0 0 |
0 1 0 0 | 0 0 0 0 |
0 1 0 1 | 0 0 0 0 |
0 1 1 0 | 1 0 0 0 |
0 1 1 1 | 1 0 0 0 |
1 0 0 0 | 1 0 0 0 |
1 0 0 0 | 1 0 0 0 |
---------------------------------
And then use karnaugh map to get the circuit of each output. You will have 4 outputs which you can use to drive the 7 segment decoder.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top