For those who want to start experimenting with a fully loaded device ready to go, the M5Stack Core2 is a great option because it includes a ~2-inch color touch screen, soft buttons, 16 MB flash and 8 MB PSRAM, a speaker with I2S amplifier, PDM microphone, 10 programmable LEDs, vibration motor, RTC, microSD slot, lithium battery, 6-axis IMU, M-Bus Socket, and Grove connector for $50 delivered.
M5Stack makes a huge ecosystem of >100 add-on modules that snap onto the bottom of the Core2's form factor, including a wide range of sensors, LoRa & cellular radios, I/Os, interfaces, servo drivers, GPS, cameras, HMDI, RJ45, UWB, RFID, etc. It's quite a clever modular expansion system that makes prototyping (or just playing around) super easy.
Note: I linked (and have) the AWS IoT Devkit version of the Core2 which comes with an upgraded battery module on the bottom vs the standard Core2 (a bit more Mah plus ten RGB LEDs built-in). It's also $10 cheaper than the base Core2 on Amazon thanks to AWS subsidy. The only difference is it comes with AWS Fire IoT Devkit firmware pre-flashed but it only takes a minute to flash it back to stock Core2 firmware.
I've been using Wemos and other various 8266 and ESP32 boards but recently picked up a M5StickC PLUS and i dont think I'll ever go back to those little standalone boards. Having everything in a nice little case with battery and most of the sensors i need, it is def a good way to go. Poked around with that FlowUI stuff and it was just too creepy to have to have my microcontroller connect to a server across the globe to program it, so a switched back to Arduino and using OTA.
The whole M5Stick ecosystem of addons it awesome too.
Yes, there's a grove connector for 3.3v on one end and more GPIO that can handle up to 5v. They have a lot of i/o on that particular device already allocated - there's a screen, a beeper, a microphone, IR and LED out, an RTC, and a 6-way motion detector, plus the buttons and a small (120mAh) battery with charging management hardware. If you are unhappy about having that much power and flexibility for under $20 you might be a little hard to please :-)
Larger units have 2, 3, or 6 grove connectors, plus a big library of pluggable peripherals.
https://www.amazon.com/dp/B08VGRZYJR
M5Stack makes a huge ecosystem of >100 add-on modules that snap onto the bottom of the Core2's form factor, including a wide range of sensors, LoRa & cellular radios, I/Os, interfaces, servo drivers, GPS, cameras, HMDI, RJ45, UWB, RFID, etc. It's quite a clever modular expansion system that makes prototyping (or just playing around) super easy.
https://shop.m5stack.com/collections/all-products/m5stack-co...
Note: I linked (and have) the AWS IoT Devkit version of the Core2 which comes with an upgraded battery module on the bottom vs the standard Core2 (a bit more Mah plus ten RGB LEDs built-in). It's also $10 cheaper than the base Core2 on Amazon thanks to AWS subsidy. The only difference is it comes with AWS Fire IoT Devkit firmware pre-flashed but it only takes a minute to flash it back to stock Core2 firmware.