| ??? 02/10/07 22:11 Read: times |
#132489 - not that fast, Kai Responding to: ???'s previous message |
Daniel said:
I had to use another xtal for a PLL Kai Klaas said:
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. Both the "bible" and the said datasheet SUGGEST that ALE may be used as a clock output. 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. Kai Klaas said:
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. It IS buggy. The specs say, VCC should be within certain limits - and while it is within these limits it whouldn't matter what waveform it exactly is. If the specs would say anything on spectral purity of VCC, I'll shut up, but nothing like that is there. Even if you are partially right that the application-maker should ensure nice and calm environment for the micro, the chipmaker should on the other hand make everything to make the chip running under any harsh circumstances - and at least make a decent documentation of what he did (and the chip should at least work within the specified limits). See Lynn Reed's approach to overdimensioning the 8255's outputs. Kai, please, this chip IS proven to be a crap. Look at AVRs and PICs. They are competition to '51s - and, although I don't like to tell it, they ARE competent. They might have a lot of errors and bugs but these are never getting worse with the newer versions - while this did! JW |
