Clarification on PCIE1 Pin Connection for Apalis iMX8 Modules with Wi-Fi

Technical Support
1

Dear Toradex Support Team,

We are referring to the Apalis iMX8 Datasheet (Doc #105526), specifically Page 17 regarding the following pins:

  • Pin 62, 64 (PCIE1_TX_N / PCIE1_TX_P)
  • Pin 68, 70 (PCIE1_RX_N / PCIE1_RX_P)

The datasheet mentions for these pins: “Pin not connected on modules with Wi-Fi”.

We have two interpretations of this statement and would like your clarification:

  1. For modules that include the Wi-Fi feature, Pins 62, 64, 68, and 70 are completely unconnected (left floating and not internally connected anywhere).
  2. Alternatively, for modules with Wi-Fi, these pins remain connected internally to the PCIE1 interface and are additionally routed to the onboard Wi-Fi module.

Could you please confirm which interpretation is correct?

Thanks
Darshan

2

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Hello Darshan,

Thank you for your detailed question regarding the Apalis iMX8 module and the interpretation of “Pin not connected on modules with Wi-Fi” for pins 62, 64, 68, and 70 (PCIE1_TX_N / PCIE1_TX_P and PCIE1_RX_N / PCIE1_RX_P) as stated in the datasheet.

Between your two interpretations:

  1. Pins are completely unconnected (floating) on modules with Wi-Fi
  2. Pins are still connected to the PCIe1 interface and also routed to the onboard Wi-Fi

The correct interpretation is the first one:
For Apalis iMX8 modules that include the Wi-Fi feature, these specific PCIe pins (62, 64, 68, 70) are not connected to the module edge connector at all. This means they are not routed to the edge connector, they do not connect to the carrier board, and they are internally used for the onboard Wi-Fi interface only. The pins are left unconnected at the board-to-board connector, and the PCIe1 interface is not available externally on Wi-Fi-enabled modules.

This design decision helps prevent any contention or signal integrity issues between an onboard device (Wi-Fi) and a potential external device.

References:

Let me know if you need any more clarifications regarding the Apalis iMX8 module pinout or usage!

Best regards,
Toradex AI Assistant.

3

Hi @darshan.vijigi ,
The pins that you mentioned are USB_01 superspeed signals which are left unconnected on the modules having Wi-Fi Bluetooth.
In case of module without Wi-FI Bluetooth, these pins are used as a PCIe (PCIE1) interface.
Please look at section 5.5 USB of the datasheet.