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ADSP-21489 SPORT and SRU signal routing

Question asked by MarcZ on May 15, 2018

Hi everyone,


We have an application which requires a two-channel serial input port and single-channel serial output port. Note that all serial ports (two input, one output) need to share the same clock and same frame sync, which are fed externally.
Our intention was to use SPORT1 as the dual-channel serial input port, and SPORT0 as the single-channel serial output port.
In our original plan, we were going to use DAI PB 19 as the Clock Input for both SPORT0 and SPORT1. We were going to use DAI PB 20 as the Frame Sync input for both SPORT0 and SPORT1. We were going to use DAI PB 11 for Input Channel 1 and DAI PB 12 as Input Channel 2. Finally we were going to use DAI PB 15 as our Serial Output channel.
We chose the pins above because of what we see on Page 10-26 of the ADSP214xx Hardware Reference: Default Routing (Con't). It shows that DAI PB 19 as a Clock input, DAI PB 20 as a Frame Sync, DAI PB 11 as SPORT DA, and DAI PB 12 as a SPORT DB. It also shows DAI Pin 15 as a DA. Sure, the exact SPORTs don't line up with our intended use (SPORT 0 and 1), but the idea was to use known pins for known functions (original clock pins for our clock functions, original sync pins for our sync functions, original data pins for data functions).
We prototyped the system with the pin definitions discussed above (in the sentence "Original plan"). But when we made a production board, we discovered that some of the pins became switched. PB 12 became the Clock, PB 11 became the Sync, PB 20 became Channel 1 in, and PB 19 became Channel 2 in.
To accommodate the mix-up in our production circuit board, we re-did the pin definitions in SRU, and the input channels do seem to work. (So far we haven't tested the output channel.)
In any event, the main question is about SRU signal routing. I know that when it comes to the SPORTS, not all pins can be used for all functions, and so I want to make sure that -- moving forward, DAI PB 12 can be used as a Clock Input signal (for a SPORT1 used as input, as well as a SPORT0 used as output); and also that DAI PB 11 can be used as a Frame Sync Input signal (for SPORT1 used as input as well as SPORT0 used as output); and also that DAI PB20 and DAI PB19 can be used as SPORT1 inputs.
Could you please confirm this?
Thank you very much