68300

Hi all

I am having nightmares getting the TPU to function.

In my current project I am running a 68376 at 25 Mhz,
   W = 1, X = 1 & Y = 24.

From this I have worked out that the TPU TCR1
frequency will be 6.3 Mhz if PSCK = 1 & TCR1 = 1,
giving me a Period of 160 Ns.

The TPU functions I am running are ITC channel 0, PMA
channel 1 and PSP on channels 2,3,4,5,6 & 7.

In my application I have 12 teeth on a sensor wheel
which equates to a spacing of 30\ufffd and at 500 RPM
which is the lowest rotational speed the time between
teeth is 10 Ms.

This gives 62,500 TCR1 counts between teeth, ( 10 Ms /
160Ns ).

Now the Motorola literature states that the TPU
measures this period to a 23 bit resolution,
so is the max count 65,536 or 8,388,608 ?

If it is 23 bit then why only pass a 16 bit parameter
" PERIOD LOW WORD " to functions runing PSP ?

My other question is the ERROR bit in the PMA
function, what is it's address ?  All other parameters
have
the format of 00FFFF channel number parameter number,
in my application I have taken it as being FFFF16.

All suggestions and advice welcomed

            thanks Roy




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