What do you consider by "very limited memory?"
The processor I generally use for my hobby projects has 16M Flash and 4M RAM. This isn't the 80's.
> Firmware is written once and seldom updated
Not these days where everything must have an App as an alternate frontend. Device Firmware Update was such a frequent request that we just made it a fixed-cost line item on our quotation forms when I worked at an engineering services company. Projects where the customer didn't want DFU were far rarer than the ones that did.
My most recent project uses an STM32F030C8 which has 64Kb of flash and 8Kb of SRAM. This is actually a beefier STM32 than I usually go for but was cheaper and more available at the time of the design.
I didn’t say it was never updated. Every IoT project or company I’ve worked on or with has the ability to update firmware and a lot of development effort goes into making sure that can happen. I have not worked at any place that pushed more updates per year than I can count on a single hand. Everything goes through, often manual, integration testing (ad nauseum in some cases), and field testing before it’s even considered as a release candidate. Compare this to release cadence of a CI driven development team for the web and server applications it connects to that deploys sometimes multiple times per day.
OK. My professional projects tend to be very large, so an 'F030 would be rather small. One of my current projects is based on an STM32F769, although I think we're using the smaller 1Mb Flash version.
DFU shouldn't get used a lot, I agree, but when it's needed it's a lifesaver.
> Firmware is written once and seldom updated
Not these days where everything must have an App as an alternate frontend. Device Firmware Update was such a frequent request that we just made it a fixed-cost line item on our quotation forms when I worked at an engineering services company. Projects where the customer didn't want DFU were far rarer than the ones that did.