MSP430F5529: Left shift of bits when oscilloscope is not plugged

Rakshan Premsagar Kapikad

Part Number: MSP430F5529

Hello there,

I am in the process of configuring the marvel PHY device with MSP430F5529. Using the USB 2 MDIO tool, i see that values of the registers are perfect while i probe in the oscilloscope.

When i disconnect the probes and have a look, the values seem to be left shifted.( Datasheet promises 141, but i get 283). How to fix this?

Regards,

Rakshan

over 5 years ago

0 Bruce McKenney over 5 years ago

Guru 95000 points

Which PHY?

If you're using SPI, check your CPOL/CPHA settings. CPOL==UCCKPL. CPHA is the inverse of UCCKPH.

0 Rakshan Premsagar Kapikad over 5 years ago in reply to Bruce McKenney

Prodigy 140 points

Marvel88e1111.

But the requirement is to have a MDIO interface.

0 Winter Yu over 5 years ago in reply to Rakshan Premsagar Kapikad

TI__Genius 12315 points

Could you test the MSP430F5529 USB2MDIO function separately and make sure it's correct?

If the issue is about Marvel88e1111, I think you can ask marvel for help.

0 Rakshan Premsagar Kapikad over 5 years ago in reply to Winter Yu

Prodigy 140 points

Hi Winter,

When you say separately, what do you mean? How do i test? Plug an oscilloscope?

Regards,

Rakshan

0 Winter Yu over 5 years ago in reply to Rakshan Premsagar Kapikad

TI__Genius 12315 points

I mean if the USB to MDIO function of MSP430F5529 is correct, you may need check your PCB layout or Marvel88e1111 chip.

Since the oscilloscope probe has load capacitance, it may cause the MDIO signal line load mismatch issue.

**Attention** This is a public forum

MSP low-power microcontrollers

MSP low-power microcontroller forum

MSP430F5529: Left shift of bits when oscilloscope is not plugged