We are using the ADSP-21489 EZ-kit and we are currently designing a custom board.
I saw some posts but I still have some questions concerning the pins that are unused.
1. About the DAI/DPI. There are some confusion between some forum posts by AD and the Hardware Reference Manual.
- The Hardware Reference Manual is mentioning (DAI Default Routing 10-24 and DPI Default Routing 10-28):
"Note that all DAI inputs which are not routed by default are tied to signal low." (10-24)
"All DPI input buffers which are not routed by default are driven low and all DPI pin buffer enable signals are driven low." (10-28)
"Regardless of the system design, it is good practice to tie all unused inputs to a high or low level to reduce dynamic power consumption." (Unused DAI/DPI Connections 10-28)
- I've tested on my board the pins that I don't use and there are all tied high (DAIs and DPIs).
- From a forum post (DivyaS) :
"The internal pull-up (ipu) and internal pull-down (ipd) resistors on 214xx are designed to hold the internal path from the pins at the expected logic levels. To pull-up or pull-down the external pads on these processors to the expected logic levels it is recommended to use external resistors."
2. About ADDR pins. Should the address lines be tied to a certain logic level?
3. About MS pins. If we do not use /MS0, should we tie high this pin?
Please clarify these points. (Also if I should assert these pins by code or by external resistors if necessary)
Thank you for your help,