| Konstantinos L. Angelis 07/07/09 03:59 Read: 316 times Lamia Greece Msg Score: -1 -1 Message Not Useful |
#166824 - Study the AT89S52 datasheets Responding to: Sivanand Somasundaram's previous message |
The AT89S52 microcontroller can sink current much better than to source.
Given this follow the simple connections as shown at 
and connect the cathode(negative) of Led to port pin and the anode(positive) through a resistor to Vcc (+5V) then when you make Low the port pin the Led should glow bright and when the port pin is High then the Led should be off. By this connection you make the port pin as a switch between ground and the Led. Also have as a reference the datasheet of AT89S52 from Atmel at http://www.atmel.com/dyn/resources/prod_documents/doc1919.pdf at point 27. (page 29) Notes: Notes: 1. Under steady state (non-transient) conditions, IOL must be externally limited as follows: Maximum IOL per port pin: 10 mA Maximum IOL per 8-bit port: Port 0: 26 mA Ports 1, 2, 3: 15 mA Maximum total IOL for all output pins: 71 mA If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test conditions. 
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| Topic | Author | Date |
| debugging AT89S52 | Sivanand Somasundaram | 06/24/09 09:52 |
| where? | Erik Malund | 06/24/09 15:08 |
| FAQs | Jan Waclawek | 06/24/09 15:19 |
| Image uploaded and other corrections made | Sivanand Somasundaram | 06/24/09 22:27 |
| You MUST use a max232 or equivalent | David Prentice | 06/25/09 01:19 |
| MAx232 connections | Sivanand Somasundaram | 06/25/09 05:37 |
| if you have connected the PC RS232 directly | Erik Malund | 06/25/09 06:15 |
| ambiguous? | Andy Neil | 06/25/09 07:02 |
| Not necessarily! | Richard Erlacher | 06/27/09 17:32 |
| Image of MAx232 connection for reference | Sivanand Somasundaram | 06/25/09 05:40 |
| 89S52 - PC -> MAX232 conenctions | Shoaib Ali | 06/25/09 06:49 |
| max 232 connection | Sivanand Somasundaram | 06/30/09 06:10 |
| To test MAX232 | Shoaib Ali | 06/30/09 17:21 |
| Testing a Com port using hyperterminal | Sivanand Somasundaram | 07/01/09 01:44 |
| PC Loop-back | Andy Neil | 07/01/09 02:13 |
| Connections of COm port | Sivanand Somasundaram | 07/01/09 04:16 |
| So what about direct on the COM port | Andy Neil | 07/01/09 08:11 |
| Check the PC's driver | Hal Albach | 07/01/09 10:21 |
| Testing an RS232 driver | Andy Neil | 07/01/09 13:13 |
| results of rs232 testing | Sivanand Somasundaram | 07/02/09 02:17 |
| Hyperterminal | Sivanand Somasundaram | 07/02/09 05:43 |
| data not displayed in echo mode in hyperterminal | Andy Neil | 07/02/09 06:08 |
| Why do you call it hypoterminal? | Richard Erlacher | 07/06/09 08:29 |
| I got confused regarding the value of capacitors | Andy Neil | 06/30/09 18:48 |
| MAx driver and hypertermianl problem solved but... | Sivanand Somasundaram | 07/03/09 04:55 |
| can somebosy please reply? | Sivanand Somasundaram | 07/05/09 05:52 |
| Try a step by step aproach | KONSTANTINOS L. ANGELIS | 07/05/09 14:53 |
| Reg Step by step approach | Sivanand Somasundaram | 07/05/09 23:08 |
| How are you programming the flash memory of AT89S52 | KONSTANTINOS L. ANGELIS | 07/06/09 02:51 |
| clarifications | Sivanand Somasundaram | 07/06/09 03:31 |
| Not to UART | Per Westermark | 07/06/09 03:51 |
| Additional info about the board AT89S52 and ISP | KONSTANTINOS L. ANGELIS | 07/06/09 11:49 |
| Many issues solved but one | Sivanand Somasundaram | 07/07/09 00:58 |
| How? | Per Westermark | 07/07/09 02:26 |
| diode...connection | Sivanand Somasundaram | 07/07/09 02:56 |
| Explain with graph or text | Per Westermark | 07/07/09 03:02 |
| clarification | Sivanand Somasundaram | 07/07/09 03:25 |
| Study the AT89S52 datasheets | KONSTANTINOS L. ANGELIS | 07/07/09 03:59 |
| Please read the answers you get | Per Westermark | 07/07/09 04:04 |
| It works now!!!! | Sivanand Somasundaram | 07/07/09 04:20 |
| What series resistor? | Per Westermark | 07/07/09 04:50 |
| Connection of diode | Sivanand Somasundaram | 07/07/09 05:33 |
| Please clarify | Per Westermark | 07/07/09 05:46 |
| the problem is NOT the 2.7V | Erik Malund | 07/07/09 06:27 |
| clarifications | Sivanand Somasundaram | 07/07/09 09:11 |
Google Ohms law  | Per Westermark | 07/07/09 09:55 |
| Report | Sivanand Somasundaram | 07/07/09 22:00 |
| Measure pin voltage when held low, not hgh | Per Westermark | 07/08/09 02:12 |
| trouble again | Sivanand Somasundaram | 07/08/09 05:25 |
| details... | Sivanand Somasundaram | 07/08/09 05:34 |
| Troll? | Per Westermark | 07/08/09 06:19 |
| clarification | Sivanand Somasundaram | 07/08/09 07:37 |
| I am not an electrical engineer I am a mechanical engineer | Andy Neil | 07/08/09 09:14 |
| Do not accept everything as is, Revise your schematic | KONSTANTINOS L. ANGELIS | 07/08/09 06:39 |
| who cares? | Erik Malund | 07/08/09 07:40 |
| Short-circuit | Per Westermark | 07/08/09 07:54 |
| OOPS, anyhow | Erik Malund | 07/08/09 08:16 |
| circuit revised but .... | Sivanand Somasundaram | 07/12/09 22:27 |
| have changed to new buffers .. | Sivanand Somasundaram | 07/12/09 23:49 |
| Post the revised schematic to check | KONSTANTINOS L. ANGELIS | 07/13/09 02:22 |
| schematic | Sivanand Somasundaram | 07/13/09 03:09 |
| there are "LED resistors" whwre are the LEDs and | Erik Malund | 07/13/09 06:28 |
| you are in deep waters | Andy Neil | 07/13/09 08:01 |
| what's the error? | Sivanand Somasundaram | 07/13/09 09:20 |
| It is hopeless, but anyhow | Erik Malund | 07/13/09 09:38 |
| Vf for diode | Sivanand Somasundaram | 07/13/09 10:32 |
| Too deep waters indeed, describe everything | KONSTANTINOS L. ANGELIS | 07/13/09 10:54 |
| then how do you propose they will both work when in patralle | Erik Malund | 07/13/09 16:50 |
| Haven't you seen that he has series resistors with each LED? | Kai Klaas | 07/13/09 19:08 |
| update | Sivanand Somasundaram | 07/13/09 21:25 |
| Resistor value | Sivanand Somasundaram | 07/13/09 23:10 |
| update.-2 | Sivanand Somasundaram | 07/14/09 04:22 |
| free-wheel diode | Per Westermark | 07/14/09 04:25 |
| details of relay | Sivanand Somasundaram | 07/14/09 04:33 |
| details of relay-2 | Sivanand Somasundaram | 07/14/09 04:37 |
| free-wheel diode always reversed | Per Westermark | 07/14/09 05:41 |
| No simple diode but a zener in series! | Kai Klaas | 07/14/09 08:32 |
| zener and IN4148 already in series? | Sivanand Somasundaram | 07/14/09 09:52 |
| clarification | Sivanand Somasundaram | 07/14/09 09:58 |
| The datasheet is a bit confusing... | Kai Klaas | 07/14/09 10:02 |
| no space to connect | Sivanand Somasundaram | 07/14/09 10:12 |
| Solder it on the solder side! | Kai Klaas | 07/14/09 10:26 |
| Thanks..but | Sivanand Somasundaram | 07/14/09 21:49 |
| Did you made a PCB ? | KONSTANTINOS L. ANGELIS | 07/14/09 15:05 |
| YEs true | Sivanand Somasundaram | 07/14/09 21:28 |
| Regarding zener and In4148 | Sivanand Somasundaram | 07/14/09 22:18 |
| update on relay testing | Sivanand Somasundaram | 07/15/09 01:12 |
| testing relay using multimeter | Sivanand Somasundaram | 07/15/09 01:25 |
| NO, NO, NO | Erik Malund | 07/15/09 06:56 |
| as opposed to | Erik Malund | 07/15/09 06:47 |
| what about the coil across the LEDs? | Erik Malund | 07/14/09 05:03 |
| full picture of relay | Sivanand Somasundaram | 07/14/09 05:11 |
| use preview | Erik Malund | 07/14/09 05:24 |
| true | Sivanand Somasundaram | 07/14/09 07:52 |
| Heaven, Erik, ... | Kai Klaas | 07/14/09 08:41 |
| it works but for relay orientation | Sivanand Somasundaram | 07/14/09 09:02 |
| Look at this, too | Kai Klaas | 07/14/09 09:03 |
| latest posts | Sivanand Somasundaram | 07/15/09 01:29 |
| Don't be so quick to experiment | Per Westermark | 07/15/09 03:11 |
| clarifications | Sivanand Somasundaram | 07/15/09 04:02 |
| make simple tests like this | KONSTANTINOS L. ANGELIS | 07/15/09 04:44 |
| reg the test circuit.. | Sivanand Somasundaram | 07/15/09 04:58 |
| circuit details | Sivanand Somasundaram | 07/15/09 05:20 |
| Still experimenting | Per Westermark | 07/15/09 05:30 |
| Already covered in this thread - more than once | Per Westermark | 07/15/09 05:21 |
| but how did the above circuit work? | Sivanand Somasundaram | 07/15/09 05:27 |
| Experiments can work, even if incorrect | Per Westermark | 07/15/09 05:48 |
| there is no zener diode | Sivanand Somasundaram | 07/15/09 07:21 |
| Don't ignore the datasheet. | Per Westermark | 07/15/09 07:42 |
| thanks | Sivanand Somasundaram | 07/15/09 09:02 |
| Forget the sales engineer! | Kai Klaas | 07/15/09 08:01 |
| Minimum turn-on voltage | Kai Klaas | 07/15/09 08:38 |
| it HAPPENS to | Erik Malund | 07/15/09 07:11 |
| ther is no other way now | Sivanand Somasundaram | 07/15/09 07:17 |
| where there is a will, there is a way | Erik Malund | 07/15/09 08:31 |
| is this what you are suggesting? | Sivanand Somasundaram | 07/15/09 09:25 |
| Relay | Steve M. Taylor | 07/15/09 15:35 |
| Finally reached the shore | Sivanand Somasundaram | 07/16/09 05:15 |
| Project completed ? | KONSTANTINOS L. ANGELIS | 07/16/09 05:23 |
| yes completed | Sivanand Somasundaram | 07/16/09 06:51 |
| Good luck! | Kai Klaas | 07/16/09 07:38 |
| Reagrding other relays | Sivanand Somasundaram | 07/16/09 21:03 |
| Scan through catalogs | Per Westermark | 07/17/09 01:05 |
| you do not need to buy there, but | Erik Malund | 07/17/09 06:44 |
| form factor | Sivanand Somasundaram | 07/20/09 03:45 |
| The datasheets normally have the answer | Per Westermark | 07/20/09 03:56 |
| files | Sivanand Somasundaram | 07/20/09 04:23 |
| Not so many files | Per Westermark | 07/20/09 05:37 |
| Regarding LEd | Sivanand Somasundaram | 07/23/09 08:13 |
| _always_ current-limited supply! | Per Westermark | 07/23/09 08:50 |
| Only if it contains a current limiting resistor! | Kai Klaas | 07/23/09 08:50 |
| thanks and file updates | Sivanand Somasundaram | 07/23/09 21:23 |
| You can enormously save user space... | Kai Klaas | 07/24/09 08:30 |
| Hard now | Per Westermark | 07/24/09 08:36 |
Correct! | Kai Klaas | 07/24/09 09:12 |
| never do that | Erik Malund | 07/15/09 07:07 |
| Kai, you must be able to see invisible ink | Erik Malund | 07/15/09 07:03 |