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nox771 / i2c_t3

Enhanced I2C library for Teensy 3.x devices
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Teensy LC/3.5/3.6 STOP not sent / detected #11

Closed Dogmans closed 6 years ago

Dogmans commented 6 years ago

Using the basic_slave and basic_master examples the handler is only triggered for the previous message, not the current one.

I.e. master sends "#1" master sends "#2" -> slave shows "#1" received master sends "#3" -> slave shows "#2" received

Is this a known issue? I've been using Teensy LC and 3.5/3.6 and it seems to affect all of them.

I suspect at some point the buffer is being filled with data but the handler is not run. On subsequent messages the buffer has additional data added to it but the count and pointer relate to the beginning of the buffer, hence the "old" data.

Currently investigating.

Thanks

Will

Dogmans commented 6 years ago

Debugging, seems to be that it triggers the handler on REPSTART, so looks like it is not seeing the stop condition at the end of the last message.

nox771 commented 6 years ago

Seems odd. Something like that should have been obvious back when the examples were created. But a lot of changes happened back then, so maybe something is off. I'll look into it.

Dogmans commented 6 years ago

Thanks, I went as far as looking at what was happening to the value of "flt" on the slave then thought I was probably out of my depth. My pullup resistors were 4K7 and I had a teensy LC connected to a 3.5, in case that makes a difference.

nox771 commented 6 years ago

I've been able to duplicate this. It appears to be something wrong in the Slave ISR code. I did change some stuff in there between when LC support got added and 3.5/3.6 support got added, so it might be related to that. LC/3.5/3.6 added STOP bit detection (which was missing entirely from earlier devices), but they didn't really document it, so it's sort of a lot of trial-and-error. It would probably not affect 3.0/3.1/3.2 devices. I'll do some more trial-and-error and see if I can get it fixed.

nox771 commented 6 years ago

I pushed an update for this. See if it works for you. On my side I've tested it between a 3.6 and LC in both directions as Master/Slave and it seemed to work.

Dogmans commented 6 years ago

Great, I'll give it a go in the next couple of days, thanks for picking this up.

Dogmans commented 6 years ago

Just tried it out and it worked! Thanks for sorting.