| ??? 04/05/05 20:03 Modified: 04/05/05 20:18 Read: times Msg Score: 0 -1 Message Not Useful +1 Underrated |
#91047 - plausible Responding to: ???'s previous message |
Andy Neil said:
Quick back-of-fag-packet calculation:
OK, so the UART syncs to the falling-edge of the Start bit, then samples each bit at its estimate of the bit's centre: -+ +---+---+---+---+---+---+---+---+---+---+ |Sta| d | d | d | d | d | d | d | d | d |Sto +---+---+---+---+---+---+---+---+---+---+ || 9.5 bits + 3% = 9.79 bits; 9.5 bits - 3% = 9.22 bits. Thus, If one end of the link is running 3% fast and the other is 3% slow, they can be half a bit adrift by the end of one character frame. In this situation, it must be touch-and-go whether the next Start bit would be correctly recognised if it immediately followed the Stop bit... So it looks like 3% must be an absolute maximum on the baud rate error (things would be worse if you add a parity bit). That seems quite plausible. 9 data bits seems like a relatively uncommon scenario though given that 8/N/1 seems to be most common these days. --Sasha Jevtic |
| 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 |