AUX_EN_P during outboard DFU

According to the “pin mapping table” on the outboard DFU guide here Notecard Outboard Firmware Update - Blues Wireless Developers
The aux serial interface (AUX_TX_P and AUX_RX_P) should be connected to the MCU host in order to enable DFU using the ROM bootloader.

However in the notecard datasheet Notecard Datasheet - NOTE-WBNA-500 - Blues Wireless Developers it states that for power consumption reasons the aux serial interface is disabled by default and must be enabled by pulling AUX_EN_P high. Can we get confirmation that the notecard is able to autonomously pull this pin high internally during an outboard DFU procedure?

If this is the case, I would suggest updating the outboard DFU docs to make it clear that AUX_EN_P will be pulled high internally, and it must be left NC in the design to avoid interfering with enabling that interface.

Hi @jascha!

You are correct, you do not need to adjust AUX_EN, in order to use Notecard Outboard Firmware Update. :+1:

You only need to make the connections shown in the pin mapping table of our documentation.

I’m not sure whether or not it is required to leave the pin NC. I will investigate and update this post.


I followed up with the firmware guys. You can do anything you want with the pin, it is not considered during the Notecard Outboard Firmware Update process. You can pull it HIGH, LOW, or float, and it will not interrupt the DFU process.

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Thank you for clarifying. I would suggest adding this note to the documentation to make that clear!