Daniel Palmer is preparing to launch a crowdfunding campaign for the BreadBee, an ultra-compact yet fully-functional Linux-based single-board computer built around an unusual Arm Cortex-A7 system-on-chip originally targeting IP cameras: the MStar MSC313E.
"The BreadBee is based on a relatively unknown IP camera SoC, the MSC313E, from a company called MStar," Palmer explains. "You might have never heard of MStar but you probably have one of their chips in your TV. There are no solutions yet that can run a real OS like Linux that can be integrated by hobbyists into boards from cheap PCB vendors that don't have show stopping limitations; i.e. the AllWinner V3s is very similar to the SoC used here but it only has one SPI controller that is lost as soon as you put SPI NOR on it.
"The MSC313E has just enough of the usual microcontroller peripherals to make it useful, comes in a (relatively) easy to work with QFN package, is tiny and costs ~$4. It is a bit harder to integrate into your designs than a microcontroller that requires a single power supply but all of the information you would need to do so is right here. The schematic for the BreadBee is incredibly simple."
Measuring just 32x30mm (around 1.26x1.18") in footprint, the compact BreadBee nevertheless boasts impressive specifications: There's a single-core 1GHz Arm Cortex-A7 with NEON instructions, 64MB of DDR2 memory, 64kB of static RAM, bootable and memory-mapped SPI-NOR, a 100Mb Ethernet port, four 10-bit analog-to-digital conversion (ADC) channels, two SPIs, an I2C bus, three UARTs, "lots of GPIO" with eight pulse-width modulated (PWM) pins, a real-time clock, watchdog timer, SD/SDIO interface, a USB PHY and host/device mux, and more.
Some of the MSC313E's hardware functionality isn't quite ready for prime-time yet, however: Present but as-yet unsupported features of the SoC include the camera interface and H.264 encoder for IP camera duties, an audio ADC and DAC, hardware cryptographic acceleration, an 8051 low-power-mode management microcontroller, "some sort of IR decoder that can wake the chip up based on the IR codes it sees," a command-queue direct memory access (DMA) controller, and an on-die temperature sensor.
More information on the BreadBee, and to sign up to be alerted when the crowdfunding campaign goes live, can be found on Crowd Supply or the project's GitHub repository; pricing has yet to be confirmed, but Palmer is hoping for production costs of around $10 per unit in small quantities.