| ??? 07/25/06 14:49 Read: times |
#121025 - Eh? Responding to: ???'s previous message |
Ammar Ahmed said:
I tried to control the intensity of one LED by the following logic.
microcontroller---to---Digital to Analogue converter---to---LED 8051 DAC 0808 LCN AT89C51 So you've given up on PWM, then? I connected the circuit diagram as shown in the following figure.
http://8052.com/users/ammarlamhay/ledglow.jpg The trouble with this is that it uses 8 pins - a whole port - just to drive a single LED! Together with the DAC, that makes for a very expensive dimmer! Are you sure that the DAC output is suitable to drive the LED? Why is there a resistor in parallel with the LED? there is only ON and OFF in electronics No, that is not true. Analogue electronics uses continuously-variable signals. Digital electronics uses signal that can be in only one of two possible states - but not necessarily "ON" and "OFF"; eg, RS232 uses positive & negative. Although each port pin is digital and, therefore, can be in only one of two states, the 8 pins of the port can together represent 256 different values. Can't you get Proteus to display that value? And, of course, the output of the DAC is analogue (well, almost - it can take 1 of 256 levels). Can't Proteus display that? |
