robismyname
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Roma_te said:For connecting several indicators together you should connect all the same name segments together (A to A, B to B, e.t.c.) and connect them (via current switch) to one port of MC (for example A to P1.0, B - P1.1, ... G - P1.6). Each pins DIG1 and DIG 2 should be connected (also via current switch) to separate pins of MC (for example P2.0, P2.7)............
I prefer attached circuit based on bipolar transistors.robismyname said:How many current switches do I need? Will this one suffice?
robismyname said:How do I design my LED's using the 8051 to have each segment be independent of one another?
Also how do I use the decimal on the LED (what pin controls the decimal)?
Roma_te said:I prefer attached circuit based on bipolar transistors.robismyname said:How many current switches do I need? Will this one suffice?
You will nead 8 switches with NPN transistors for current ~1A and 7 switches with PNP transistors for current ~150 mA.
The triangle on this diagram - 5VDCrobismyname said:For the PNP transistors in your diagram you have the base wire going to the MCU and Emitter wire going to ground...
Roma_te said:The triangle on this diagram - 5VDC
Yesrobismyname said:Ok so 5 volts for PNP Emmitter triangle and 5 volts for NPN base triangle?
For switch off all indicators you should output on P2 XXXX0000 (X-any bit, 0 or 1);robismyname said:Any need for a truth table?
Roma_te said:For switch off all indicators you should output on P2 XXXX0000 (X-any bit, 0 or 1);
For switch on 1-st indicator - P2=XXXX0001;
For switch on 2-nd indicator - P2=XXXX0010;
For switch on 3-rd indicator - P2=XXXX0100;
For switch on 4-th indicator - P2=XXXX1000;
ONE EQU 0Ch ; single digit (low nibble)
TEN EQU 0Dh ; LH digit (upper nibble)
Update_Disp:
mov dptr,#display_table
mov a,one ;copy one digit to acc
movc a,@a+dptr ;get digit from offset in acc
ret
;0 = 028h, 1 = 07Eh, 2 = 019h, 3 = 01Ch
;4 = 04Eh, 5 = 08Ch, 6 = 088h, 7 = 03Eh
;8 = 008h, 9 = 00Eh
;
display_table:
db 00101000B,01111110B,00011001B,00011100B
db 01001110B,10001100B,10001000B,00111110B
db 00001000B,00001110B
ctownsend said:That is wrong. Maybe I am missing something here, but if your displays are CC (common cathode) This is the correct way to wire it up.
The given idea is good for small 7 segment display but if you are using large 7segment displays then you will have to bring change in it like using ULN 2003 on all segments (A-G).robismyname said:ctownsend said:That is wrong. Maybe I am missing something here, but if your displays are CC (common cathode) This is the correct way to wire it up.
To clarify all displays are common cathode.
So you are telling me that I dont need NPN's on the dispaly pins (A-G) going to the MCU ports? Only PNP's on the common cathode pins of the displays going to the MCU ports?
Can I use PNP - PN2 222A 749 instead of BC327-25 or 2N3904?
robismyname said:Can I use PNP - PN2 222A 749 instead of BC327-25 or 2N3904?
sn_burki said:The given idea is good for small 7 segment display but if you are using large 7segment displays then you will have to bring change in it like using ULN 2003 on all segments (A-G).
sn_burki said:The given idea is good for small 7 segment display but if you are using large 7segment displays then you will have to bring change in it like using ULN 2003 on all segments (A-G).
There are several ways of solutions this problem:electronproton said:but the problem is my 7805 become very hot when the seven segment ON.what should i do?
are you aware that common anode would require pnp transistors instead of npn? The power would be switched instead of gnd.electronproton said:I'm using common anode seven segment..
the circuit is similar to ctownsend schematic..
show us your circuit. what is the current rating of your 7805?electronproton said:but the problem is my 7805 become very hot when the seven segment ON..
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