Hardkernel Unveils $30 Raspberry Pi Compatible Module with RTC, ADC, and LiPo Battery Support
Hardkernel is better know for its ODROID boards powered by Samsung Exynos SoC. So I was surprised to discover ODROID-W, “a miniature computing module which is fully compatible with all software available for the Raspberry-Pi”. Software compatible, really? Yes, because they used the same Broadcom BCM2835 SoC found in the Raspberry Pi, packaged it in a smaller form factor, while keeping HDMI, USB, and CSI interface, and expansion headers, and all that for $30, plus just $9 for shipping.
Let’s go through ODROID-W specifications first:
- SoC – Broadcom BCM2835 ARM1176JZ-F processor @ 700 Mhz with VideoCore IV GPU
- System Memory – 512MB LPDDR2 (Samsung K4P4G324EB PoP)
- Storage – microSD slot + eMMC socket (bottom of the board)
Video Output – micro HDMI (with NXP IP4791CZ12 protection IC)
- USB – micro USB connector, and USB host (not soldered)
- Expansion Headers:
- R-Pi compatible 26-pin expansion header (through holes)
- R-Pi compatible 15-pin CSI connector
- 20+6 -pin header for extra GPIO/ADC/Power and USB connection
- RTC backup battery connector (1.25mm pitch Header)
- Li-Po battery connector (1.25mm pitch Header)
- Misc – RTC
- Supply – Via micro USB or LiPo battery
- PMIC – Ricoh RT5T619 Power Management IC with step-down DC/DC Converters, low-dropout regulators, Real Time Clock, Li-ion Battery Charger, I2C-Bus Interface, Voltage detections, Thermal shut-down, and 12bit Analog-Digital Converter. (0 to 2.5V)
- Step-up DC/DC converter – TI TPS61259 . For battery-powered portable applications. Supports up to 1000-mA load current from a battery discharged as low as 3.4V. The 5 Volt output is used for USB host and HDMI circuitry.
- Voltage detector IC – Torex XC61FN2412MR for stable system start (Auto-power on) It includes Voltage detector and Delay circuit
- Dimensions – 60 x 36 x 7mm
Hardkernel created this board thanks to a request from a customer for a wearable platform. ODROID-U3 consumes too much power, and the Raspberry Pi was just too big. So they created a software compatible module for this purpose, which explains why we lose Ethernet, composite output, the audio jack, one USB port, and the DSI connector, and the SD card slot has been replaced by a micro SD slot, but keep everything else, and gain RTC, 2x ADC, LiPo, and eMMC socket, a few more GPIOs (32 in total), all into a much smaller form factor. Current documentation and resources include the schematics (PDF), the mechanical drawing files (DXF), Linux 3.12 source code with RTC, ADC, etc.. drivers, and ODROID-W Wiki.
The video below shows how you can solder the USB connector to the top or bottom of the boards, and boot the battery-powered board with Raspbian installed on the micro SD card. Nothat if you want network connectivity as well, you’ll need to add a hub. Alternatively, you could also use their $20 W Docking Board for the module which adds 4 USB ports, 10/100M Ethernet, a 3.5mm stereo audio jack, and a UART port for the serial console.
There’s also another interesting video showing how to make your own smartwatch with ODROID-W.
Hardkernel ODROID-W can be pre-ordered now for $30 + $9 for shipping payable by Paypal, with shipping starting on August 26. There are also various accessories such as the W docking board with or without a TFT LCD display, a connector pack (USB + headers), RTC backup battery, a 750 mAh battery, and more.
Thanks to Nanik for the tip.