| ??? 03/18/05 05:08 Modified: 03/18/05 05:10 Read: times |
#89891 - Where is the difference between... Responding to: ???'s previous message |
Geert said:
When pressing the switch, the level on P0 goes low (switch makes contact with ground) and the LED is deactivated. So, this is OK too.
But when releasing the switch, the level on the pin P0 remains low!!! (measured this with a scope). and later he said:
I can only have it working fine, when I directly connect P0 to ground or +5Vdc, so no switch nor resistor involved! Where is the difference between grounding the pin via switch or 'directly'? This makes no sense to me. Your switch isn't damaged, is it? What happens to the pin's potential (look at it with scope), if you only read the PCF8574? By the way, do NEVER connect any I/O pin directly to +5V!! Only via current limiting resistor (pull-up)! Kai |
| Topic | Author | Date |
| Problems with PCF8574 input | 01/01/70 00:00 | |
| best guess | 01/01/70 00:00 | |
| To Erik | 01/01/70 00:00 | |
| So.... | 01/01/70 00:00 | |
| To Jez Smith | 01/01/70 00:00 | |
| show the code | 01/01/70 00:00 | |
| To Oleg | 01/01/70 00:00 | |
| How to post code | 01/01/70 00:00 | |
| To Andy | 01/01/70 00:00 | |
| hmmmmmm | 01/01/70 00:00 | |
| To Jez | 01/01/70 00:00 | |
| RTFDS - using 8574 IO as inputs | 01/01/70 00:00 | |
| To J. Guy | 01/01/70 00:00 | |
| When is pin written ? | 01/01/70 00:00 | |
| My datasheet tells something different.. | 01/01/70 00:00 | |
| To Kai | 01/01/70 00:00 | |
| cutting through the fog | 01/01/70 00:00 | |
| To J. Guy | 01/01/70 00:00 | |
| Where is the difference between... | 01/01/70 00:00 | |
| To Kai | 01/01/70 00:00 | |
| Re:Problems with PCF8574 input | 01/01/70 00:00 | |
| Test it without having any communication | 01/01/70 00:00 | |
| To Kai | 01/01/70 00:00 | |
| Maybe good guess! | 01/01/70 00:00 | |
| To Medhi | 01/01/70 00:00 | |
| Switch terminology | 01/01/70 00:00 | |
| Thanks! | 01/01/70 00:00 | |
| Coonfoosed yeeet | 01/01/70 00:00 | |
| Contact arrangement - nothing else | 01/01/70 00:00 | |
| PCF8574 | 01/01/70 00:00 | |
| To Ben | 01/01/70 00:00 | |
| I have used the bugger often | 01/01/70 00:00 | |
| To Erik | 01/01/70 00:00 | |
| helloooooooooo !! | 01/01/70 00:00 | |
| To Erik | 01/01/70 00:00 | |
| Wager... | 01/01/70 00:00 | |
| To Grant | 01/01/70 00:00 | |
| The code... | 01/01/70 00:00 | |
| Thats told 'em :-) | 01/01/70 00:00 | |
| Frightend... ;-) | 01/01/70 00:00 | |
| Formatting | 01/01/70 00:00 | |
| Format flavours. | 01/01/70 00:00 | |
| Insanity | 01/01/70 00:00 | |
| Malaysian Grand Prix... | 01/01/70 00:00 | |
| Some update!!! | 01/01/70 00:00 | |
| Let me comment.... | 01/01/70 00:00 | |
| "fancy" code | 01/01/70 00:00 | |
| I'll Suggest... | 01/01/70 00:00 | |
| Pointers and structures | 01/01/70 00:00 | |
| C assumes int | 01/01/70 00:00 | |
| Followed the advice of Michael Karas... | 01/01/70 00:00 | |
| Why not assembly using? | 01/01/70 00:00 | |
| Assembler code | 01/01/70 00:00 | |
| Well... | 01/01/70 00:00 | |
| int | 01/01/70 00:00 | |
| Check Maxint ? | 01/01/70 00:00 | |
| Maxint | 01/01/70 00:00 | |
| Murdered quote | 01/01/70 00:00 | |
| I2C code | 01/01/70 00:00 | |
| Keil webpage | 01/01/70 00:00 | |
| i2c simulator | 01/01/70 00:00 | |
| Me to blame? | 01/01/70 00:00 | |
| not blaming you! | 01/01/70 00:00 | |
| Michael B. made a very usefull tool! | 01/01/70 00:00 | |
| hello | 01/01/70 00:00 | |
| Not aware? | 01/01/70 00:00 | |
| thank u | 01/01/70 00:00 | |
Name confusion... | 01/01/70 00:00 | |
| hi | 01/01/70 00:00 | |
| Damned, damned, damned... | 01/01/70 00:00 | |
| Ha, ha, ha, ha, ha .... | 01/01/70 00:00 | |
| Calico | 01/01/70 00:00 | |
| Pls. do so! | 01/01/70 00:00 | |
| Keyboard Calico | 01/01/70 00:00 | |
| Christmas | 01/01/70 00:00 | |
| Maybe it was .... | 01/01/70 00:00 | |
| Christmas Presents | 01/01/70 00:00 |