MC33937A SPI SO output voltage too small

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MC33937A SPI SO output voltage too small

527 次查看
jgerhardy
Contributor III

Hello,

I am starting up an MC33937A which is connected to a MagniV controller (S12ZVML). I hope this is the right place to post this, since it seems to be a problem with the 33937, but maybe there is something in the configuration of the SPI on the S12ZVML.

There are clean signals on 1) SCLK  2) MOSI, and 4) /CS from the MagniV, however the signal on the 3) MISO from the 33937 is strange (at least not as I would have expected it), seems too small to be read by the MagniV and SPIF does not set after the data have been sent (see blue line in attached scope shot). The power on VDD of the 33937A is 5V and stable. At the moment I have not a clue where else I can look for the cause. Any help is greatly appreciated.

Regards,

John

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448 次查看
jgerhardy
Contributor III

Hello,

Just to complete things, a good nights rest and the the mistake materialized. The wire connecting to the MISO pin had a bad connection (cold solder joint). A little heat, re-connected the wire and the signal looks good ...

Regards,

-John