What happens if I have a fleet `_fw` environment variable and then later add an identical device `_fw` variable?

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1

For weird reasons, I have a bunch of devices in a fleet that have the following fleet env vars:

_fw        = V1_3_3$20260923000412.binpack
_fw_retry  = 1790660860

I was updating host firmware using the fleet env var, but I ran into a problem: some small number of devices in the fleet already had a device env var for _fw that preempted my fleet env var.

The easiest way for me to resolve this problem is to just set the _fw device-level env vars for all the devices in the fleet. I would do this using the Notehub UI – I would request a host ODFU for every device in the fleet (using the Select All and then Update buttons).

My question is: if a device is already running _fw = V1_3_3$20260923000412.binpack because it took it from the fleet environment variables, when the device level _fw is set to the same firmware version will the Notecard ODFU the host again, or is the Notecard smart enough to know that the host is already running the requested host firmware version?

Why this matters: our device is extremely energy constrained. ODFU is really expensive for us energy-wise, so I want to make sure I don’t spend that energy on a redundant host ODFU.

2

Hi @daterdots,

There is some nuance here to understand:

  1. If the _fw AND _fw_retry are the same, (or _fwc/_fwc_retry), no one will even notice that there was a difference, regardless of whether it came from device or fleet.
  2. For Notecard firmware, if the _fw is the same but _fw_retry is different, the Notecard will check the MD5 of what it’s already running, and it will be optimized out. No impact.
  3. For Host firmware, if the _fw is the same but _fw_retry is different, in no case will it be re-downloaded, but it will change from “completed” back to “ready” state, which means that…

…for Inboard (IAP) DFU, the host will see that it has become ‘ready’ again and it is responsible for checking MD5 to see if it needs to ‘pull’ it from the Notecard again. If it’s the same it is up to the host to just set it back to ‘completed’.

…for Outboard DFU, the Notecard re-burns the firmware onto the host mcu and restarts it, and marks it ‘completed’.

Thanks,
Rob