IMX8MP Wifi/BT LED activity

Technical Support
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1

Hello,

We are working on bringing up a custom carrier for a Verdin 8MP and we have some LEDs wired to the module-specific pins for WIFI and BT activity.

However, the LEDs remain on and do not blink while e.g. performing a bluetooth scan or connecting to WiFi and generating some traffic.

I see there is a similar issue already for the IMX6 where it turns out the lines do not actually function but remain high. Could you confirm if this is also an issue with the iMX8MP module?

Thanks!

2

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Wi-Fi and Bluetooth Activity LED Status on Verdin iMX8M Plus

Based on the Verdin iMX8M Plus V1.1 datasheet, the Wi-Fi and Bluetooth activity LEDs are indeed available on module-specific pins (1). The documentation shows these signals in Table 29: Module-specific Signal Pins of the AW-CM276NF on SODIMM Connector:

  • Pin 188 (MSP_43): GPIO[2]/WLAN_LED - Wi-Fi activity LED (Output) (1)
  • Pin 176 (MSP_38): GPIO[3]/BT_LED - Bluetooth activity LED (Output) (1)

LED Functionality

The activity LEDs are controlled by the AW-CM276NF Wi-Fi/Bluetooth module itself, not directly by the i.MX 8M Plus SoC (1). The LED behavior depends on the firmware loaded into the AzureWave module (1).

Potential Issues

If your LEDs remain constantly on and don’t blink during Wi-Fi or Bluetooth activity, this could be related to:

  1. Firmware Configuration: The actual LED behavior depends on the specific firmware loaded into the AzureWave module (1)
  2. Module Initialization: The LEDs are outputs from the Wi-Fi/Bluetooth module, so proper module initialization is required
  3. Default State: The LEDs may have a default “on” state when the module is powered but not actively configured for activity indication

Verification Steps

To troubleshoot this issue:

  1. Check Module Detection: Verify that the Wi-Fi/Bluetooth module is properly detected and initialized in your system
  2. Monitor GPIO States: You can monitor the actual GPIO states of pins 188 and 176 during Wi-Fi/Bluetooth operations
  3. Firmware Status: Ensure the AW-CM276NF module is running with appropriate firmware that supports LED activity indication

The LED functionality is hardware-dependent on the AzureWave module’s firmware behavior rather than being directly controlled by the SoC, which may explain why they don’t respond as expected to network activity (1).

Best regards, Toradex AI Assistant.

3

Unfortunately the Wifi module datasheet only mentions the LED pins once and does not go into detail on their functionality so I am unclear on how to go about finding more information about whether the firmware is expected to support this. It would be odd for the datasheet to explicitly mention an activity LED but then not provide this functionality by default.

4

Could you please specify exactly which module pin you have wired?

Could you please provide more details? The Colibri iMX6 module does not include a Bluetooth/Wi-Fi module, so I’m not sure how this relates to your original question.

5

Hi @alex.tx,

I was referring to this thread, sorry - WIFI / Bluetooth Activity Led details - #2 by jaski.tx

It seems that currently these pins are always high and not controlled by the firmware of the WiFi chip.

Naturally it’s a different WIFI module, but not implausible a similar situation exists based on our observations.

In any case, we have wired:

  • SODIMM 188 (MSP_43) to a WIFI LED
  • SODIMM 176 (MSP_38) to the BT LED.

Hope that helps clarify.

6

Yes, those pins are wired directly to the AW-CM276NF module’s GPIO2 and GPIO3. These pins are controlled exclusively by the Bluetooth/Wi-Fi module firmware, and the Toradex BSP cannot control them. This is the same as explained in the ticket you referred to. The Colibri iMX6ULL module features the same Bluetooth/Wi-Fi module as Verdin iMX8m Plus.

7

Yes, it is understood that these pins’ behaviour is controlled by the module and not the iMX8. Do you have any resources that provide more information as to the expected behaviour of said module? Findings are somewhat sparse online.

8

The AW-CM276NF module is based on the NXP 88W8997 chipset (formerly Marvell 88W8997), and unfortunately, NXP does not provide us with details about its firmware. I would recommend posting your question regarding the 88W8997 firmware on the NXP Community Forum.

9

Thanks, we’ll connect with our NXP contacts

10

If you happen to receive a relevant response, would you be so kind as to share it here?

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11

Sure - will do!

12

Official word from NXP is that this functionality is not implemented in the current firmware.

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