68300

Now Roy,

I think you should be a little more careful here.  In the last line of your email, you said that any advice would be welcome.

That sure opens a fairly wide window.

Yes, indeed, when you are running the PMM/PMA - PSP - ITC function, you only pass a 24 bit parameter.  There is PPWA_Lower_Word and PPWA_Upper_Byte.  You DO NOT get 32-bit resolution here, you get 24-bit resolution.

I know a guy that has written a fairly good algorithm on the missing / additional tooth and I can turn you on to him if you like.

Regards,

Charlie

-----Original Message-----
From: Roy [mailto:spectric@...]
Sent: Wednesday, May 08, 2002 6:02 AM
To: 68300@yahoogroups.com
Subject: [68300] TPU problems



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? 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




__________________________________________________
Do You Yahoo!?
Yahoo! Health - your guide to health and wellness
http://health.yahoo.com


---------------------------------------------------
To unsubscribe from this group, send an email to:
68300-unsubscribe@yahoogroups.com

To learn more about Motorola Microcontrollers, please visit
http://www.motorola.com/mcu

 

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/