MSP432-RTOS: MSP432P401 I2C master hangs after common spikes on SDA / SCL

DJ-NG

Part Number: MSP432-RTOS
Other Parts Discussed in Thread: PCF8575

Hi folks!

I use I2C (100/400 KHz) within POSIX/TI-RTOS (SL SDK 3_30) talking without problems to couple of I2C IO expanders PCF8575.

Driver usage is like SDK examples for I2 master (Non blocking, No timeout).

Caused (reproduceabe) by external radiated disturbance in logic analyzer I see a aprox 60ns spike setting SCL=SDA=0 at same time .

After this event I2C transfer stops immediately and I assume MSP432 driver hangs in a undefined state.

I tried to filter spikes by ceramic caps, but this does prevent the issue.

So I need to find a workaround to make I2C run again after these spike events.

Some ideas to this:

- If this irregular state is not detectable by SW, do I have restart I2C periodicly (by close() and open() again ) to abort such a state ?

- I do not use timeout.. does timeout make driver come out of these kind of states ?

Any ideas very welcome!

over 3 years ago

0 Gary Gao over 3 years ago

TI__Mastermind 39730 points

Hi DJ

What's the glitch time do you setting? Are you keep the default value?

0 DJ-NG over 3 years ago in reply to Gary Gao

TI__Genius 9355 points

Yes, I recently looked at that, I used default setting.

This seems to work good as problems occurs with spikes > 50ns (I measured 60ns ++) .

0 Gary Gao over 3 years ago in reply to DJ-NG

TI__Mastermind 39730 points

The timeout feature just used as clock stuck at low for long time. I think you should figure out where the glitch come from, the pull up power or some slave devices and I think add a capacitor will be helpful on signal line or the power line.

0 DJ-NG over 3 years ago in reply to Gary Gao

TI__Genius 9355 points

Hi Gary!

Definitely its betetr to minimize glitches by some HW adding. I am about investigating here more.

But I ask myself, if there is a way, to bring hanging USCI_B I2C up again by some SW workarounds ?

Rest of MCU is still working.

Q: is there a suggestion to re-initialize I2C again druing runtime to bring USCI_B into a working state again ?

Actually only a reset helps..

0 Gary Gao over 3 years ago in reply to DJ-NG

TI__Mastermind 39730 points

The problem actually is how to detect the I2C hung up by this kind of issue by software. You can enable the SCL low timeout feature incase the SCL maybe poll low in some hung up case. You may also enable the watch dog to monitor this event.

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MSP432-RTOS: MSP432P401 I2C master hangs after common spikes on SDA / SCL