| ??? 02/09/07 17:13 Modified: 02/09/07 17:15 Read: times Msg Score: +1 +1 Good Answer/Helpful |
#132382 - Not neccessarily bugs... Responding to: ???'s previous message |
Daniel said:
- ALE misses one pulse on each MOVX instruction That's no bug, but a well known fact. Read the last line of page 11 of this document: http://www.nxp.com/acrobat_d...ARCH_1.pdf Daniel said:
AT89S8252 not With this micro one ALE is skipped during MOVX instructions too, as stated in the according datasheet. Read page 5 of this document: http://www.atmel.com/dyn/resou...oc0401.pdf Daniel said:
I had to use another xtal for a PLL It's never a good idea to use the ALE signal for anything else than it's originally designed for, namely as address latch enable signal. Daniel said:
- With little spikes in Vcc (500mVpp)(I know, they should not be there!) AND low temperature, the AT89S8253 is unable to read eeprom in the very beginning of software execution. It's very well known, that spikes on Vcc is deadly poison to all flash micros. By the way, 500mVpp is not at all little but huge! That the AT89S8252 withstands this torture only tells, that the AT89S8252 is especially noise immune, but not that the AT89S8253 is bugy. Daniel said:
- Vcc rise time is critical (2ms max). Otherwise, internal clock become unstable (half the speed, for example) This mainly depends on your reset circuitry. More, the presence of these 500mVpp spikes you reported makes me believe, that your design is unproper. Daniel said:
- Previous "bug" eventually solved adding 10ms "dummy" delay after reset and before any EEPROM reading. Why, why?? Again, what you call a bug might just be the consequence of a noisy and unproper design. Kai |
