We are considering a project where WiFi functionality would be phased in later. Is it possible to use Imp005 with only an Ethernet connection? If so, would we need to have Blink up working at that time, or could we phase that in too?
Yes, it is possible to use it with only ethernet (right now it picks ethernet in preference to wifi).
You can skip end user blinkup by doing this at the factory, then the user can just plug ethernet in to have it working (as long as they have a DHCP server that serves DNS & a correct default gateway).
However, if you want to enable wifi later, you’ll still need to complete the RF portion of your design, along with any approvals that might be necessary, before you ship.
Note that current imp005 firmware will unconditionally attempt to use Wifi if Ethernet link is lost, or if the server connection drops.
The ability to disable Wifi completely is currently being developed and is expected to be made available in a subsequent firmware release.
If there’s no Wifi HW present (antenna etc), that means Wifi connection will also fail. What would be the effect of that on the code running on the device (assuming it is set up to continue running after connection loss) ?
It’d behave like any imp without connectivity? ie, it’d come up and run code from a cold boot (after the 10s holdoff). If your code doesn’t block on needing a network connection, then it’ll just run offline.
You need blinkup for factory provisioning, but you could put the circuit on a factory fixture PCB and connect the output (BLINKUP_DIN) via a pogo pin to a test point on the UUT.
Obviously, removing blinkup means that the end user has no way of setting additional parameters - eg a local proxy address, static IP, etc - which is why we recommend you keep this circuitry on your product even if most users never use it.