PSA: If you're a fan of ATmega, try AVR Dx
Fans of classic 8‑bit AVR microcontrollers are highlighting Microchip’s newer AVR Dx and Ex families as powerful, low‑power alternatives to popular 32‑bit parts, thanks to their robust 5 V‑tolerant I/O, rich mixed‑signal peripherals (op‑amps, differential ADCs, event systems, programmable logic), and simple tooling. Others counter that cheap ARM and RISC‑V MCUs like STM32, ESP32, and CH32V003 offer far more CPU performance, memory, and connectivity for similar or lower prices, especially when projects need Wi‑Fi or complex software stacks. Alongside the technical trade‑offs, participants weigh sourcing strategies—AliExpress versus reputable distributors—raising concerns about counterfeit chips, supply‑chain reliability, and the value of paying more for good documentation, support, and predictable availability.
AVR Dx/Ex vs other MCUs
- Some argue cheap 32‑bit parts (STM32G0, ESP32, CH32V003, RP2040, etc.) make 8‑bit AVRs obsolete on cost/performance.
- Others say AVR Dx/Ex target different needs: simple 8‑bit core, strong mixed‑signal peripherals, 5V operation, deterministic timing, and very low power.
- Compared to STM32G0, AVR DD/DB/EA/EB are described as “barebones but peripheral‑rich”; STM32G0 wins on MHz and RAM, AVR on analog and glue logic.
- AVR Dx is also compared to PIC: similar rich peripherals, but PIC cores and proprietary toolchains are viewed as weak points.
Peripherals and mixed‑signal strengths
- Highlighted features: multiple on‑chip op‑amps, 12‑bit differential ADC with gain (EA/EB), dual‑supply I/O and built‑in level shifting (DD), event system, configurable logic (3‑LUTs + flip‑flops).
- These let designs replace external op‑amps, logic, level shifters, and some I2C ADCs, often making the MCU cheaper than discrete alternatives.
- Some note new PIO‑like / programmable logic behavior and offloading of tasks (e.g., quadrature decoding) from the CPU.
GPIO robustness and 5V tolerance
- Several hobbyists value classic AVR/Arduino for 5V, “abuse‑tolerant” GPIO and ease of breadboarding, claiming they survive shorts and overvoltage better than 3.3V boards (Pi, ESP).
- Others point out most MCUs have ESD diodes and can tolerate higher voltages if input current is limited; some STM32 pins are 5V‑tolerant.
Tooling, debugging, and languages
- Older AVR era is remembered fondly for open, Linux‑friendly tooling vs early PIC.
- Today, ARM and RISC‑V ecosystems (SWD, open toolchains) are praised; some “don’t miss” avr‑gcc/avrdude, others still like them.
- UPDI on new AVRs is liked for its simplicity; it also supports on‑chip debugging.
- Debate over languages: some prefer C/assembly and direct register work; others like MicroPython/CircuitPython and Arduino‑style C++ for ease.
- Rust for AVR reportedly works since the core is unchanged.
Supply chain, pricing, and counterfeits
- One view: low Chinese marketplace volume suggests AVR Dx/Ex are “too early” for risk‑averse commercial designs.
- Counterview: OEM and major distributors have ample stock; relying on grey‑market China pricing is misleading.
- Multiple comments warn about counterfeit AVRs/STM32s on AliExpress; others report good experiences.
- Philosophical split: buy cheap from AliExpress vs pay more to support local distributors or well‑documented vendors (e.g., Adafruit).
Boards and entry‑level advice
- For beginners, suggestions range from AVR Dx Arduino‑core boards to ESP32, RP2040 (Pico), CircuitPython boards, and low‑cost RISC‑V devkits.
- Common theme: prioritize simplicity, robustness, good docs, and ecosystem over raw specs.