| ??? 08/09/06 17:29 Read: times |
#121916 - PNP? Responding to: ???'s previous message |
Is this an arbitrary choice, or does it reflect some advantage of which I'm not aware? There are on pullups that I can measure or otherwise observe on any of the matrix lines.
made with PNP transistor derivers? What's the benefit of pulling down rather than pulling up the one currently driven row/column? multikey for one, it is a heck of lot easier to handle a 'wired or' in negative than in positive logic Erik |
| Topic | Author | Date |
| High or Low in keypad scanner? | 01/01/70 00:00 | |
| PNP? | 01/01/70 00:00 | |
| maybe with TTL, but what about CMOS? | 01/01/70 00:00 | |
| I would not, the user does | 01/01/70 00:00 | |
| that depends on how you scan the inputs | 01/01/70 00:00 | |
| physical/technological reasons | 01/01/70 00:00 | |
| What sorts of reasons? | 01/01/70 00:00 | |
| early MOS technology | 01/01/70 00:00 | |
| Maybe they did it... | 01/01/70 00:00 | |
| Oxymoron! | 01/01/70 00:00 | |
| you spoilt my joke now | 01/01/70 00:00 | |
| Jokes | 01/01/70 00:00 | |
| We are living in a TTL world... | 01/01/70 00:00 | |
| I don't know why this interests me, but ... | 01/01/70 00:00 | |
| a proverbial answer | 01/01/70 00:00 | |
| So you figure it's just a matter of preference? | 01/01/70 00:00 | |
| You really should get out more! | 01/01/70 00:00 | |
Yes, it's a second childhood ... or maybe a third | 01/01/70 00:00 |