It looks like it is too late to warn you off these things
However I'm more into traditional uC development, where you code in a proprietary dev set if tools or IDE, flash the prototype, test, debug, flash, ad naseum... these things are literal multithreaded computers, and quite complex compared to basic single-task micros.
Which is why after 5 years learning Pi's and Linux I was very, very happy to find Ulitbo.
It works as a traditional IDE, but it has multicore and multitaking built-in, so I can learn that outside of Linux, whew.
And it even does Aarch64 QEMU
Swap the SDcard and it is full Raspbian Desktop PC. Actually a Ultibo kernel.bin can run from same card, just edit config.txt
uS precision timing is required, or where an interrupt MUST take priority over everything including any UI component,
Well it is an VC4 with attached A series ARM cpu, better use a R series if you want real time.
Tricky timing stuff I have not yet figured out how to do on the Pi I can do on a tiny 8pin PSoC micro controlled via the i2c.
But the Pi's CPU does run ~1GHz, should be able to use that speed for something.
The hardware on the Pi like timer/counters is basic but no one has really used them much yet.
I only just found out about GPCLK0/1/2, which could be useful. Then there is FIFO/DMA, hidden i2c's in the SPI hardware.
Weird serial uarts, PDM, PCM, SMI, most with minimal datasheet info and examples, any example likely to be in Linux.
Traditional uC stuff gets expensive once you want to add connectivity like Ethernet which is why I first used Pi's, plus I got HDMI for free, down side was learning Linux and the babel of languages that run on it.
Let's just say I know Linux better than DOS or Windows now, not sure how all that learning can fit in my tiny brain.
You can extract as much as you want, it oozes out of my ears these days
WiFi now has all those ESP8266 chips/modules and their new bigger cousins. Might have to earn WiFi too, but wait, I have Pi3's and a Zero W now. Never really liked WiFi for sensors, too power hungry, rolled out a mesh network years ago.
Long range Bluetooth looks possible, but LoRa is now my preferred RF sensor method, but I only do 1-5minute updates to save power. 10hz? Many options just no 1 year batteries
The Display situation is MUCH better than it used to be, nowhere near what it could be yet.
We need a bunch of real plug n play DSI displays, from 0.5" to 14". There is a market there, we don't have to use Arduino LCDs. DPI TFTs are looking easier to use, just don't expect many I/O to be left
That 40 way header on the Pi's means daughter or motherboards are simple, most of mine are even single sided.
I do have an advantage in that we have our own PCB making facility.
Embedded ARM's, Cortex M0's are so cheap now, M3, M4, M7 all useful little gadgets.
Lazarus/FPC can compile for some of these, Ultibo could be the IDE if the hardware stuff is ported.
OpenOCD, OpenJTAG interface to the micro's? Well there is a JTAG footprint on all Pi's.
Not only does OpenOCD run on Pi3, your could use Pi's to bit bang JTAG to other micro's or Pi's.
With Ultibo I can already remotely upgrade the kernel.bin but recently I think now I can upgrade any connected uC that does the timing/control stuff
Now your Analog sampling requirement, i2c will do 16-24bit 10hz no probs, even 100hz.
Faster than that and SPI is better. Number of bits and sample rate?
The control stuff can be off loaded to a uC, it is the comms stuff the Pi is good.
Trying to do control and comms in a single uC?
Well look at the latest IoT uC chips like PSoC6, it has two cpu's, M4 plus M0.
It is now easier to add cpu cores to silicon, letting you choose what does control and comms.
Pi2/3 have multicores, one core for comms, one for control, leaving two for redundancy?
Latest tablet/phone chips have big.LITTLE cores now.
Multicore uC are the future. a 64bit ARMv8A A35 core is 0.4mm square, that's cheap realestate on a piece of silicon.
Have you tried writing code for a single uC that does everything?
Takes a long time to verify it all works and testing is crazy.
Pi2/3 are nice cheap multicore hardware to learn this stuff on.
With Ultibo no Linux gets in the way, it is only just over a year old, but it will take me two years to learn the stuff I want to learn on it.
instead of developing FOR a device, I'll develop ON the device. It is definitely a shock to the system.
It still does my head in, I can remote ssh into a gadget from a 100km away and edit/change some running shell script on the fly and it still works. Linux shell is ok for slow stuff, collecting data every few minutes etc and it is reliable, still got stuff running after years.
I use piCore for this Linux, smaller, easier to maintain.
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges