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AD2S1205: incremental encoder emulation failure

Question asked by afab on Apr 10, 2012
Latest reply on Apr 24, 2012 by afab



I confronted with encoder emulation failure,

My board dos not correctly work with AD2S1205, but work with AD2S1200  :-) The same board!!!

The encoder emulation with AD2S1205 is not comparable with AD2S1200.


The reset time at rdc is the same. (300ms) The crystal is the same (8.192MHz) The position vailue (from parallel port) show alwais correct in all cases (with  AD2S1205 and AD2S1200) When Resolver is plugin, i have no LOT and DOS failure.


The difference, what i see:

When Resolver is disconnected of AD2S1205, then clock the A and B signals of Encoder with 1,024MHz and correct offset.

By AD2S1200, the same A and B signals of Encoder are clocking with 256kHz. The LOT and DOS failure are active in both cases.


When resolver is stopping, i see by AD2S1200 encoder outputs the last active value (0 or 1),

but the AD2S1205 encoder outputs (A and B) generates futhermore a kind of pwm signal sequence with correct offset. (see picture: signal A)

By AD2S1200 emulation generate the encoder 1024 impulses per rotation, but the follower ic generate a kind of pwm signal sequence. (very much more than 1024 impulses)


I'm already tested two ic AD2S1205, with the same result. :-(


Operate the encoder emulation by AD2S1205 of the same kind as by AD2S1200? Are the encoder output driver the same?