I have bought Keil's MCB167-NET Evaluation Board. The board uses SAK-C167CS-LM as microprocessor. To gain more knowledge about the microprocessor I have searched for documents about it on google. I have found documents about SAK-C167CS-LM AB-step and SAK-C167CS-LM BA-step etc.
What does BA-step and AB-step mean?
What does SAK stand for?
The documents I have found says that its a 25 MHz microprocessor, but the evaluation board runs at 20 MHz. Why?
I would appreciate any links to sites that gives a good description of either the evaluation board or the microprocessor on a beginners level.
In short different revisions. Check Infineon's site for documentation and errata sheets for details on the differences. The flash version of the 167CR family had different bugs in each revision (On the upside at least Infineon appears to publish their errata sheets).
Again RTFM. Infineon uses different prefixes for different temperature ratings. Well documented in the datasheets.
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The above link is to Infineion's summary page for the 167cs with links to data sheets, user manual and errata sheets. You definitely want to read at least the appropriate data sheet, the user manual and the errata sheets.
Any number of reasons are possible. One of the more likely is to maximize the speed of the processor using economical external memeory. Running at 20MHz with no wait states can be faster than running at 25MHz with wait states. Check Hitex's web site they have a nice reference manual for users just starting with the 167 family. It will probably provide some illumination on configuaration and startup, particularly the external bus system.
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There site has a number of interesting notes. I've used their ICE to advantage before.
You could be right. But anyway I think Robert Adsett gives other, more possible reasons. I have seen many boards with CAN controllers using crystals only selected for the best match of any serial UART bit rate. With 25 MHz the Infinoen CAN can be used with nearly every common CANopen, (without 1 Mbit/s) and with all DeviceNet bit rates.
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