| Gopal Amlekar 01/10/10 09:09 Read: 670 times Pune India |
#172317 - ADC0809 problem |
Hi,
I am interfacing an ADC0809 with Microchip PIC18F4550 (Wait.. it is also related to 8051). To channel 1 of ADC0809, a potentiometer voltage divider is connected. What happens is this input voltage is at 4.5V initially till ALE pulse goes high. The moment ALE goes high (As per ADC datasheet, ALE rising edge latches address data into the ADC) this voltage drops down to 2V. ADC then measures this 2V and outputs equivalent digital data. Strange thing is this does not happen with 8051(P89V51RD2). The input voltage is not at all affected. This is what it should be. I have compared program flow (both progams are in C), pulse widths, timings, voltage levels on pins etc. of 8051 and PIC and found no significant difference. Anyone can guide what can be the cause or how to troubleshoot it? Thanks p.s. I am posting this thread on microchip forum too. |
| Topic | Author | Date |
| ADC0809 problem | Gopal Amlekar | 01/10/10 09:09 |
| Is the very same ADC chip in both cases? | Daniel Contarino | 01/10/10 09:51 |
| From time to time... | Kai Klaas | 01/10/10 14:22 |
| Datasheet read, same hardware | Gopal Amlekar | 01/11/10 02:53 |
| Define 1000000000% | Per Westermark | 01/11/10 06:48 |
| Thoughts... | Kai Klaas | 01/11/10 09:04 |
| Solved partially | Gopal Amlekar | 01/13/10 04:06 |
| So the cap did help? | Kai Klaas | 01/13/10 08:56 |
| RE: That cap did help? | Gopal Amlekar | 01/15/10 06:48 |
The input multiplexer is damaged!  | Kai Klaas | 01/15/10 08:49 |
| Discharge diode | Per Westermark | 01/15/10 10:14 |
| RE: The input multiplexer is damaged | Gopal Amlekar | 01/16/10 02:01 |
| Indeed, a very poor design!!! | Kai Klaas | 01/16/10 09:38 |
RE: Indeed, a very poor design!!! | Gopal Amlekar | 01/17/10 06:27 |