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unused pin for 21587

Question asked by hanhsu on Nov 17, 2016
Latest reply on Mar 22, 2018 by saml

Hi Sir,

 

We are designing the ADSP-21587 and reference SC589 since they share the same datasheet and EVB. Compare w/ SC589, the ADSP-21587 doesn't support SD/SDIO/eMMC (MSI), MLB, EMAC, USB, and PCIe function (table 2 of datasheet).

 

As study the table 26 of the datasheet, I got some information as below.

 

For MSI, they can map to "PF_x" pins, type is "InOut".

For MLB0_SIG/DAT/CLK, type is "InOut" for automotive model.

For eMAC, they map to  "PA_x", "PB_x", "PF_x", "PG_x" pins, type is "InOut".

For USB and PCIe, map to "USB0/1_x", "PCIE0_X". type is "InOut"

----------------------------------- The note of Table 26 ----------------------------------------------

USB0/1_VBUS:  Connect to GND if not used

USB0/1_DM:      Add External Pull Down if not used

USB0/1_DP:       Add External Pull Down if not used

USB0_ID:             Connect to GND when USB is not used

VDD_USB:           Connect to VDD_EXT when USB is not used

USB0_VBC:         Add External pull down if not used

 

VDD_PCIE:          Connect to GND if not used

VDD_PCIE_TX:   Connect to GND if not used

       VDD_PCIE_RX:  Connect to GND if not used

 

      PCIE0_RXM/P: type is InOut, connect to ??

      PCIE0_CLKM/P: type is InOut, connect to  ??

      PCIE0_TXM/P: type is InOut, connect to ?? 

      MLB0_SIGN/P: type is InOut, connect to  ??

      MLB0_DATN/P: type is InOut, connect to ??

      MLB0_CLKN/P: type is Input, connect to ?? 

      Px_x (GPIO, multi function): type is InOut, connect to ??

------------------------------------- End  ------------------------------------------

The questions as below.

1. For above unused pins, how do we connect it?    

 

2. Can we according the type (Input, Output, InOut, a, g, s) to have a the general rule for the unused pin? Like if type is "input", we should connect to GND w/ resistor if unused? If type is "Output", it can keep floating if unused?

 

3. Some note shows "Add External Pull Down if not used", can the pin tie to GND directly? if not, any suggest value of resistor? 1K? 10K?

 

Thank you.

Han

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