The Rimer SBC is a development board based on a Microchip SAMD51 Cortex-M4 microcontroller and designed as a complete standalone playground with a built-in display, keyboard, audio input and output, a few I/Os, and a 18650 battery holder.
It is specifically based on the Microchip ATMSAMD51J20A microcontroller, running at 120MHz with 1MB of flash memory and 256KB of RAM, and utilizes many of the peripherals available in the TQFP64 package. The board includes a 3.2-inch 320 x 240 IPS TFT LCD connected via high-speed SPI and a 40-key mechanical keyboard scanned via an I2C GPIO expander. It also features an amplified 700mW speaker output and buffered analog input and output is routed via the 3.5mm audio jack.
The Rimer SBC’s standalone nature makes it suitable for on-the-go development, rapid prototyping, and educational purposes without the need for external hardware. The maker also plans to port DOOM II and other DOS video games to the platform.
It can be powered over USB-C and supports LiPo and Li-ion batteries (with integrated charging circuits) for portable use. We’ve covered plenty of Arm Cortex-M4 development boards like the CANBed M4, Banana Pi BPI-EAI80, and a variant of the STM32 Black Pill. But it’s the first time we’ve come across a standalone Cortex-M4 computer, although the Wio Terminal could be considered a portable computer (without a keyboard) based on the same SAMD51 microcontroller.
Rimer SBC specifications:
- MCU – Microchip ATSAMD51J20A
- Core – Arm Cortex-M4F @ 120MHz
- Memory – 256KB RAM
- Storage – 1MB flash
- Storage – SD/MMC card interface, 64KB I2C EEPROM
- Display – 3.2-inch 320×240 IPS TFT LCD with optional capacitive touchscreen, running up to 60fps
- Audio – Onboard 700mW speaker
- USB – USB 2.0 via USB-C port
- Peripherals
- 1x serial port (UART, I2C) with 3.3V @ 125mA power output
- 2x 6-lane GPIO ports with 3.3V @ 300mA each and configurable as digital I/O,
- SPI, UART, USART, I2C, TC and TCC
- Buffered analog I/O routed to 3.5mm audio jack.
- Power Supply
- 5V via USB-C
- 16850 battery socket with onboard charger
- 20mm x 60mm LIPO battery with onboard charger
- Dimensions – TBD
The Rimer SBC runs a FreeRTOS-based operating system called ucosR, featuring a command-line interface with command history, scripting support, and a basic text editor. It also includes Basic-D—a BASIC language interpreter with line editing and syntax highlighting—and a ZX Spectrum 48K emulator with debugger support and compatibility with .z80 and .sna snapshot files. Firmware and software for the project are available on the project’s GitHub account whose wiki’s section has some basic hardware documentation.
The Rimer SBC development board is priced at $240 on Tindie, and a soldered Li-ion 18650 battery socket can be added for $5.
Tomisin is a writer specializing in hardware product reviews, comparisons, and explainers. He is very passionate about small form factor and single-board computers.
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