| ??? 04/05/05 16:56 Read: times |
#91033 - additional error Responding to: ???'s previous message |
Jon Ward said:
If you can get everything with 1%, communications will be OK. There is an another error to be considered. Typically, there is some skew in the edges of the pulses, and this tends to be assymetrical. So a "1" comes out longer or shorter than a "0" in a "1010" pattern. Even worse, sometimes this skew depends on the previous bits and/or exhibits change over time, slow or fast (jitter). The source of this error are numerous - type of cable and how it is laid, layout of PCB, type of level converting chip and its supply, spurious currents flowing through the cable/shield... As a simple illustration, on my desk I have a pretty standard 2m cable and ST232BN - quite an ideal situation, and the assymetry between "1" and "0" bits is around 0.3us. Fortunately, this gets not accumulated through a byte. Now this is not too much at 9600 bauds where bit time is around 100us, but at 115200 baud, where a bit time is around 8.7us... Jan Waclawek |
| Topic | Author | Date |
| Comm. Between 8052 & PC | 01/01/70 00:00 | |
| Whats the baud rate? Is it PC compatible | 01/01/70 00:00 | |
| Baud rate error | 01/01/70 00:00 | |
| baud rate tolerances | 01/01/70 00:00 | |
| some thoughts | 01/01/70 00:00 | |
| Baud rate errors | 01/01/70 00:00 | |
| baud rate errors/2 | 01/01/70 00:00 | |
| How about this? | 01/01/70 00:00 | |
| Serial Timing | 01/01/70 00:00 | |
| additional error | 01/01/70 00:00 | |
| plausible | 01/01/70 00:00 | |
| Oops! | 01/01/70 00:00 | |
| Cable? Speed? | 01/01/70 00:00 | |
| More on cables | 01/01/70 00:00 | |
Check cable pins | 01/01/70 00:00 | |
| PC Software? | 01/01/70 00:00 | |
| Really? | 01/01/70 00:00 | |
| Line termination: Some - not most | 01/01/70 00:00 | |
| Line termination | 01/01/70 00:00 | |
| GetLine ?! | 01/01/70 00:00 | |
| Exactly | 01/01/70 00:00 | |
| VB6 | 01/01/70 00:00 | |
| Some How!! | 01/01/70 00:00 | |
| another option | 01/01/70 00:00 | |
| Unspecific English | 01/01/70 00:00 | |
| Platform-Specific Line Termination | 01/01/70 00:00 | |
| Extra Line | 01/01/70 00:00 | |
| Lines, Platforms, and dead-end threads | 01/01/70 00:00 |