Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

can somebody tell me what's missing in this design

Status
Not open for further replies.

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
i am building this mmd and its not working if something is missing in this ciruit i attached the pic please see
 

d@nny

Full Member level 5
Joined
May 28, 2011
Messages
246
Helped
11
Reputation
22
Reaction score
11
Trophy points
1,298
Activity points
3,238
where is your MMD Design
You forget to include it
 

d@nny

Full Member level 5
Joined
May 28, 2011
Messages
246
Helped
11
Reputation
22
Reaction score
11
Trophy points
1,298
Activity points
3,238
what is the function of mclr pin?
is this Digital I/O?
If not pull it up with maximum 10k resistor
 

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
i am building this mmd and its not working if something is missing in this ciruit i attached the pic please see


---------- Post added at 14:32 ---------- Previous post was at 14:29 ----------

actually i want to know that i have to add more parts to this design like pnp transistors like bc640 to the rows and i am using column cathode and row anodes is it correct
 

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,032
Trophy points
1,393
Location
Greece
Activity points
64,375
If you intend to use row multiplexing (row1..row2..row3... of all displays) then you need a device that can provide more current, 74138 can't do much
 

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
so what should i use then please advice i made this and its working like hell some columns were running from left to right no charcters
 

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,032
Trophy points
1,393
Location
Greece
Activity points
64,375
you can either use discrete transistors or a device like UDN2981 , you need something that can provide the current needed when all the columns of a row turn on
 

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
please be specific if i add transistors to the columns or to the rows why its not showing any characters if there's some problem with hardware or software>?
 

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,032
Trophy points
1,393
Location
Greece
Activity points
64,375
it should be working fine in proteus , if it is not then it is a software issue.
In the real circuit you have to drive the rows with devices that can provide enough current to light the leds
 

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
please be specific if i add transistors to the columns or to the rows why its not showing any characters if there's some problem with hardware or software>?

---------- Post added at 14:58 ---------- Previous post was at 14:53 ----------

is there any substitute of udn2981 coz its not avaiable
 

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,032
Trophy points
1,393
Location
Greece
Activity points
64,375
Your circuit will work fine in proteus for simulation because the model of U7 doesn't have a limited current output like in reality so fix your software first so it can work and then you can add the transistors to provide the needed current in the rows.
 

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
please tell me what should i change in the software i am newbie in programming
 

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,032
Trophy points
1,393
Location
Greece
Activity points
64,375
I have no idea about PIC mcu so I can 't help you on that but you haven't provided any source code so I don't see how anyone could answer to what is wrong with your code
 

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
shall i post here the complete code or make it zip and post then
 

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,032
Trophy points
1,393
Location
Greece
Activity points
64,375
whichever suits you, if it is in more that one source file or if the code is long use zip
 

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
here's the code
 

Attachments

  • recompiled.rar
    84.9 KB · Views: 11

get2leo

Junior Member level 3
Joined
Sep 21, 2010
Messages
30
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
india
Activity points
1,439
see i uploaded the code please help me out
 

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,032
Trophy points
1,393
Location
Greece
Activity points
64,375
your code is written in basic so not everyone will be able to help because most users use code written in C
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top