STM32F4 I2S Full Duplex: Is Double Transmit possible?

phil2 · ‎2014-01-11

Posted on January 11, 2014 at 10:45

Hello,

I've been spending some time looking through the STM32F4 reference document and it looks quite clear that the I2S2 / I2S2ext are supposed to be used in a full-duplex configuration.

However, I'm curious, is it possible to configure I2S2 as TX and I2S2ext as TX at the same time and use them independently ( transmit two different words at the same time )?

Thanks,

Phil.

#stm32-i2s-duplex

waclawek.jan · ‎2014-01-12

Posted on January 12, 2014 at 17:41

Probably yes, but why don't you go and try yourself?

JW

phil2 · ‎2014-01-13

Posted on January 13, 2014 at 09:01

I'll give it a go. Didn't want to waste my time if someone knew if was definitely impossible.

Thanks,

Phil.

phil2 · ‎2014-02-14

Posted on February 15, 2014 at 08:28

Okay, it didn't take long to determine that this is not possible. Spending a bit of time looking at the DMA table in the reference guide shows that both the I2S TX and I2Sext TX are on the same stream, but different channels. As you can't use two channels on the same stream it looks like the I2S Extended really is full duplex only.

Thanks,

Phil.

waclawek.jan · ‎2014-02-16

Posted on February 16, 2014 at 23:16

> Okay, it didn't take long ...

... a mere month ... ;)

(sorry, I couldn't resist)

Well, it does not mean that only duplex operation is possible - you just might need to device a different way how to deliver the data...

Besides, what you said is entirely true only for I2S2 - for I2S3, separate streams are available for ''main'' and ''ext''.

JW