The brightness is low (with or with out) the TIP127???
The resistor pack: is it pull up or pull down? What value?
To turn on a LED what do you do?
>Is "A" high and "1" low? OR Is "1" high and "A" low?
>What voltage to turn on the LED? 1.8 volts?
The 8051 Port0 only pulls down. The resistor pack is the only pull up on port0.
The other ports pull up but not well. In this diagram I show a internal 500 ohms to show how bad the old 8051 pulls up.
Here I added a 2N2907 to amplify the pull up current of Port2. (this inverts the output so in software you will need to invert the data sent to port2!!!!!
R12 10k limits the base current for Q2. (about 0.4mA) (maybe 3.3k is better)
With the 2N2907 or MPS2907 will pull up hard.
You might need R14, 100 ohms to limit the current for the LED. (resistors on each segment and DP)
Do not use the TIP127.
I think I leave from this project. Its have lot of drawbacks. It does not have the decimal point. If it have, its good for me. Thats why I think leave from this project. Can you any Idea to make another one or any link? I have the keil code for this project. Please have a look for it
Anyway, Thank you for attension and replays about my project. Have a nice time.
Calculators are easy.... There are enough people here to help.... I would drive the LED screen via shift resisters and simple npn's to get the brightness... The problem is just usually the time to update... When I use several LED modules, I almost always use an interrupt to drive the LED display so I keep the duty cycle constant!!
If the duty cycle is too low then you won't see anything... As for the floating point.. Most compilers have ftoa() for such purposes...
Calculators are easy.... There are enough people here to help.... I would drive the LED screen via shift resisters and simple npn's to get the brightness... The problem is just usually the time to update... When I use several LED modules, I almost always use an interrupt to drive the LED display so I keep the duty cycle constant!!
If the duty cycle is too low then you won't see anything... As for the floating point.. Most compilers have ftoa() for such purposes...