| ??? 11/24/09 22:30 Modified: 11/24/09 22:32 Read: times |
#171139 - Configured as push-pull? Responding to: ???'s previous message |
Yash said:
I am monitoring temperature using an ADC0848(8 input channel ADC). However the digital output of the circuit remains fixed at 1111 1111 even after the end of conversion( actually,the 8 bit output remains the same as that of the port of my microcontroller board where it being given. In the above instance , since I have made the port an input port by making it 1111 1111, the output also remains the same after EOC) If you write a "1" to a port pin of a standard 8051, then the port behaves like an input, being able to accept high level and low level from a driver. But only if the port is set to quasi-bidirectional mode. Modern clones of 8051 can have the port configured as push-pull-output, emitting a strong "1" after writing a "1" to the port pin. Then, the port cannot accept low level, but tries to force a "1", which results in a short circuit condition of course, very probably damaging the micro or the driving circuit. So, take care that the port isn't configured as push-pull-output!! Which micro do we talk about here? Kai Klaas |
| Topic | Author | Date |
| Receiving output from ADC0848. | 01/01/70 00:00 | |
| Don't feed other pins without VCC | 01/01/70 00:00 | |
| CS and RD working. | 01/01/70 00:00 | |
| Wrong understanding of ADC! | 01/01/70 00:00 | |
| But according to Mazidi... | 01/01/70 00:00 | |
| No, you don't! | 01/01/70 00:00 | |
| Sorry! | 01/01/70 00:00 | |
| How do you see that? | 01/01/70 00:00 | |
| The LCD shows a 255. | 01/01/70 00:00 | |
| But this can have zillions of reasons... | 01/01/70 00:00 | |
| Never retype source code when posting | 01/01/70 00:00 | |
| Working! But with errors... | 01/01/70 00:00 | |
| You must convert raw ADC reading into temperature | 01/01/70 00:00 | |
Self-heating? | 01/01/70 00:00 | |
| Configured as push-pull? | 01/01/70 00:00 | |
| It's a P89v51RD2 | 01/01/70 00:00 | |
| Difference only noticeable if contention | 01/01/70 00:00 | |
| then STOP what you are doing | 01/01/70 00:00 |