| ??? 05/20/10 15:00 Read: times |
#176074 - In reference to the above: Responding to: ???'s previous message |
In many circuits, you can't just select a crystal based on "best" baudrate matching for the simple reason that the UART isn't the only device in need of a specific frequency. There may be needs for a specific clock frequency for CAN or USB or similar, and the other devices may expect clock frequencies with many zeroes in them.
But as the clock frequencies of the processors are constantly climbing, it gets easier and easier to divide the input clock and get a close enough baudrate. In reference to the above: if you have another "device in need of a specific frequency" make sure you choose a processor where T2, T3 or T4 will be available for baudrate generation - OR - choose one of the few with a dedicated baudrate generator. The granularity using the higher numbered timers is so much better. Erik |
| Topic | Author | Date |
| Baud RateTolerance? | 01/01/70 00:00 | |
| acceptable baud-rate error | 01/01/70 00:00 | |
| 100% ?? | 01/01/70 00:00 | |
| 2.5% | 01/01/70 00:00 | |
| whoa!! | 01/01/70 00:00 | |
| I prefer < 0.5% | 01/01/70 00:00 | |
| the method | 01/01/70 00:00 | |
| skew/asymmetry | 01/01/70 00:00 | |
| Asymmetry | 01/01/70 00:00 | |
| ZERO | 01/01/70 00:00 | |
| So do I... | 01/01/70 00:00 | |
| Not always possible to select crystal just for UART | 01/01/70 00:00 | |
| In reference to the above: | 01/01/70 00:00 | |
| Thank you all. | 01/01/70 00:00 | |
| Try a test with a PC and Sqr Sig Gen | 01/01/70 00:00 | |
| likely a wromg approach | 01/01/70 00:00 | |
| Maxim AN-2141 | 01/01/70 00:00 | |
link and comment | 01/01/70 00:00 |