| ??? 03/01/05 21:47 Read: times |
#88811 - Determining direction Responding to: ???'s previous message |
Direction can be determined in moment n as An XOR B n-1 that is if value of one channel is different than previous value of the other channel (the previous state). In my application I had the readouts as edge interrupt routines triggered with any edge of the encoder (some discretes to transform all edges of 2 channels into falling edges on INT pin) but if the speed isn't too high, you can poll for value change.
Also a good sanity check is that nybble composed of An, Bn, An-1, Bn-1 has always odd number of bits set (hint: PSW.P bit) for all legal transitions. Even number of bits set means either the transition didn't happen (the wheel didn't move) or you lost a count, i.e. due to too fast rotation. |
| Topic | Author | Date |
| Digital position encoder | 01/01/70 00:00 | |
| Dont do this. | 01/01/70 00:00 | |
| Signals are not connected directly | 01/01/70 00:00 | |
| Is assembly ok? | 01/01/70 00:00 | |
| For Mehdi | 01/01/70 00:00 | |
| its easy in software | 01/01/70 00:00 | |
| but | 01/01/70 00:00 | |
| same resolution | 01/01/70 00:00 | |
| But...what if ? | 01/01/70 00:00 | |
| So what is the solution? | 01/01/70 00:00 | |
| absolutely no problem | 01/01/70 00:00 | |
| Thank you | 01/01/70 00:00 | |
| PLEASE not again | 01/01/70 00:00 | |
| Sorry | 01/01/70 00:00 | |
| list.hw.cz | 01/01/70 00:00 | |
| thank you | 01/01/70 00:00 | |
| Re: PLEASE not again | 01/01/70 00:00 | |
| Re frequency | 01/01/70 00:00 | |
| So what frequency do we sample at? | 01/01/70 00:00 | |
| I try to explain Peter's idea again | 01/01/70 00:00 | |
| We know it ! | 01/01/70 00:00 | |
| Nothing ??? | 01/01/70 00:00 | |
| it takes time | 01/01/70 00:00 | |
| Code doesn't function | 01/01/70 00:00 | |
| reverse direction ! | 01/01/70 00:00 | |
| This is not a problem | 01/01/70 00:00 | |
| incorrect operation? | 01/01/70 00:00 | |
| right connection ? | 01/01/70 00:00 | |
| I dunno | 01/01/70 00:00 | |
| Now... | 01/01/70 00:00 | |
| check the sample condition ! | 01/01/70 00:00 | |
| clarify | 01/01/70 00:00 | |
| @Erik | 01/01/70 00:00 | |
| @Peter | 01/01/70 00:00 | |
| Grey code | 01/01/70 00:00 | |
| Grey code more | 01/01/70 00:00 | |
| Grey INCREMENTAL ? | 01/01/70 00:00 | |
| I guess 98 | 01/01/70 00:00 | |
| Gray code | 01/01/70 00:00 | |
| Not a gray code | 01/01/70 00:00 | |
| Grey | 01/01/70 00:00 | |
| Yes of course its Grey code | 01/01/70 00:00 | |
| Absolute Vs Incremental | 01/01/70 00:00 | |
| So now... | 01/01/70 00:00 | |
| Yes it can but only... | 01/01/70 00:00 | |
| Peter is right! | 01/01/70 00:00 | |
| Lover not a fighter :-) | 01/01/70 00:00 | |
| Lover of software | 01/01/70 00:00 | |
| steps lost or not | 01/01/70 00:00 | |
| Determining direction | 01/01/70 00:00 | |
Its not Grey, its Gray ! | 01/01/70 00:00 |