| ??? 02/05/05 11:51 Read: times |
#86617 - 3rd way Responding to: ???'s previous message |
Peter Herbst said:
First is to use 390ohm resistors this will give 10mA per portpin so if all are on you get 80mA. But then the LED's are not so bright. If that's a problem, maybe use higher efficiency LEDs? Second is to use software to cheet our eyes. Switch the LED on and off at 100-120 Hz and turn always only the half of them on. So they seem to be on all at once but as you swith them the controller has to drive only 4 at once. This will also reduce the brighness - because the LEDs are only ON for half the time! The 3rd way is to add some sort of external "buffer" that does have sufficient current capability. This could be simple discrete transistors, or a suitable IC. |
| Topic | Author | Date |
| required AT89c2051 help on leds | 01/01/70 00:00 | |
| P1.0 and P1.1 input only | 01/01/70 00:00 | |
| Ignore earlier post | 01/01/70 00:00 | |
| trying to understand | 01/01/70 00:00 | |
| oh, by the way re posting code | 01/01/70 00:00 | |
| Check the datasheet | 01/01/70 00:00 | |
| to much | 01/01/70 00:00 | |
| Circuit Details of Led's | 01/01/70 00:00 | |
| to much for all | 01/01/70 00:00 | |
| 3rd way | 01/01/70 00:00 | |
Solution works | 01/01/70 00:00 | |
| ASCII schematic of Peter Herbst solution | 01/01/70 00:00 |