Duplicate mode registers

Bill Franke

On page 173 of the "SX-Key/Blitz Development System Manual 2.0" it shows duplicate CMP_B, WKPND_B, WKED_B, and WKEN_B registers. They seem to share $08,$18; $09,$19; $0A,$1A; $0B,$1B addresses respectively.

I have some hand written notes (written several years ago) that say they are not the same registers and can't be interchanged. So which ones do I use? The book seems to use the lower addresses for the interrupts in it's examples, but then what are the higher ones for? Is this a typo? Would appreciate any help here.

Bean

They are not duplicates. On the SX48, the lower values are used to READ the register, the higher values are used to WRITE to the register.
On the SX28, only the lower values are available, and they WRITE to the registers. Kinda weird, but that's how it works.

Bean.

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The needy are many, the deserving are few.

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Bill Franke

Then it must be a typo since the lower values say "write" or "exchange" just like the higher values do.
Gunther must have cut and pasted because he has the exact same thing on page 220 of his book.
Thanks Bean.

Bill

Guenther Daubach

Bill,

hmm...

For "Exchange CMP_B with W" and "Exchange WKPND_B with W" you may set M to either $08, or $18 resp. $09, or $19 because such registers are exchanged, i.e. they are read and written within just one clock cycle, moving the current content of W into the selected !RB, returning with the former content of the !RB register in W.

For M settings $0A, $0B, $1A, and $1B, I must admit that I simply took the information found in the SX48 datasheet, and replicated it in the table on page 220 of my book without really testing that. Let me check this on a real SX48, and I'll let you know the results later.

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Greetings from Germany,

G