How to create STM32F407G-DISC1 intercom system?

[s.kirill]

Hi! I am trying to create an intercom system with STM32F407G-DISC1 boars, where one speaks and every listen. I am little bit confused about how to configure cs43l22 codec and if this concept will work. Or it is better to create PDM bus?

Thank you.

[Ozone]

I suspect, no.

First, I2C is a bus with a dedicated master, and up to 127 slaves. Each slave must have his own (unique) address.

Second, the throughput. Not sure of your required bandwidth, but you would need to run the lowest common denominator (probably 1 MBit/s).

Third, the bus itself. I2C means "Inter-IC" bus, the hardware requirements (levels, timing) was specified with chips on one PCB in mind. Remember, the ACK bit requires a reversal of the SDA direction. Pretty sure this will spell trouble on long cable connections.

My first consideration would be ethernet / UDP.

[s.kirill]

Thank you for your answer, but it seems that you mixed up i2c and i2s.

[Ozone]

You are correct.

Data channel to the codec is I2S, which would solve the bandwidth question. The was a control channel to the codec IC via I2C, if i remember correctly.

But still, electrical signal transfer and coordination of this multi-master approach remain to be sorted out. Neither was this bus intended to work over long cables.

I suppose you speak of a star-shaped configuration, with several meters of cable to each peer.