| ??? 11/19/11 19:09 Read: times |
#184812 - Answers Responding to: ???'s previous message |
Per Westermark said:
It probably took two years, because either the data sent out changed or you handling of the data (master or slave side) changed because of the actual values. Or maybe the processors didn't run with crystals (except for the RTC) and the baudrate drifted slightly. I always use crystal oscillators, used a completely new master board and analysed the data on PC RS485 to 232 converter and I was getting Junk data which worked when I added the 1msec delay. My serial module has been used since 1992 and I never had a problem with it. The issue here is that the extra ms needed means your software wasn't rugged enough. For two years, it was running on the margin, but you had failed to identify this critical flaw. It's no different from having a design running at just below the temperature where it fails, or at just the limit of how low voltage the processor can work with. All software development for embendded projects needs to set up a long list of critical limits, and then try to validate that there are ample safety margins. It's important to know that the slaves have whatever safety margin they need when picking up every single byte from the UART. Did you test with a higher baudrate or shorter delays than what you used for the final release? Yes I actually tested with shorter delays than 1ms and they didn't work, 1 msec or greater delays worked for 19200 baud rates. I didn't test other baud rates. I used the settings and equations for baud rate in the datasheet and verified my results with picbaud calculator and error was 0.16% at crystal frequency of 4MHz. Could this be the reason? |
| Topic | Author | Date |
| NXP Promises ARM Cortex-M0 in DIL Package! | 01/01/70 00:00 | |
| Amazing! I thought DIL was DEAD. | 01/01/70 00:00 | |
| Me too! | 01/01/70 00:00 | |
| Hmm.. | 01/01/70 00:00 | |
| maybe | 01/01/70 00:00 | |
| dsPIC is a waste of time | 01/01/70 00:00 | |
| We Await The Results... | 01/01/70 00:00 | |
| Which one(s)? | 01/01/70 00:00 | |
| two | 01/01/70 00:00 | |
| Why so long? | 01/01/70 00:00 | |
| Well | 01/01/70 00:00 | |
| Two years | 01/01/70 00:00 | |
| Answers | 01/01/70 00:00 | |
| But what delays did you try before original release? | 01/01/70 00:00 | |
| shorter delays | 01/01/70 00:00 | |
| good thinking | 01/01/70 00:00 | |
| Can't get the error | 01/01/70 00:00 | |
What changed? | 01/01/70 00:00 | |
| Seems a little harsh | 01/01/70 00:00 | |
| Never blame manufacturer without proofs | 01/01/70 00:00 | |
| Proven Product Syndrome | 01/01/70 00:00 | |
| My response ... | 01/01/70 00:00 | |
| No Offense | 01/01/70 00:00 | |
| What I Do and Not Do | 01/01/70 00:00 | |
| NXP are mistaken | 01/01/70 00:00 |