HC908 problem with mon08

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Hi,

I have some trouble with connecting my USB-Pemicro pod to a MC68HC908QY4.

The first design I built had a socketed DIP chip onboard and worked as
expected. Then I switched to an SMD and now I can not connect anymore. Now
it tells me:


Postload command file correctly executed.
Opening USB Port 1 ...MON08 MULTILINK Interface cable detected - Flash
Version 2.11
Could not measure target baudrate.
Opened.
Starting powerdown reset sequence ...

Trying Security $FFFFFFFFFFFFFFFF Invalid/No Response.
     (Failure of 68HC08 to respond properly. Check connections.)


Which I think is a good Idea - if I hadn't already done it often enough :-)
(yes - for the different SMD pinout) and I also can not find any shorts or
broken lines.

When I watch the connection process with a mixed signal scope I can see all
MON08 signals do what they are in my eyes supposed to do, just PTA1
(directly connected to pod) will not go up far enough (goes from low to some
800mV while trying to connect). Also the signals look qite lousy (a lot of
10MHz noise from the pod) which they do on the DIP-Board, too.

Also if i am simply wire-wrapping a QY4 SMD type to my pod and pull up the
reset pin I have the same behaviour while a wire-wrapped DIP board with the
same connections works perfectly.

Could it be that I have missed some Information about the SMDs or is it the
same die?

Do DIPs have any additional Cs or protection inside?

Any Idea?

Thanks,
Henrik



Re: HC908 problem with mon08

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Have you checked the levels of all pins against the table in the manual
listing the requirements for entering monitor modes? You have to supply
proper logic levels to some of them.

Do you have 9.83something MHz clock source?
If you rely on internal osc - the OSCTRIM value may or may not be factory
programmed. If it's not programmed the communication won't work. And
contrary to what the manual says it was't programmed in any of the chips I
had.




Re: HC908 problem with mon08

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Yes, I have. I have a very nice mixed mode Scope on my Desk where i can see
exactly what happens on VDD, VSS, PTA0, PTA1, PTA4, OSC1, RST and IRQ.
Everything looks fine, just the stupid PTA1 won't go high because obviously
the smd is driving it low (Pod drives high when contact is open).

... anyway it still should work when the chip is empty which it does not,
right?

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Yes, it is in the USB adaptor.

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Ah!

I already wondered about that. I can't monitor my other toys without clk.
The Pemicro manual is not too clear about that either. It just says "Pin x
is CLK", which I interpret as "connect directly to OSC1 as with the clocked
MAX232 circuit".
I hope that is right.

Thanks for the help,
Henrik



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