The original DARwIn-OP Robot uses an on-board 1.6 GHz Intel Atom Z530 computer and a CM-730 ARM controller board. This controller board includes a 3-axis gyro, a 3-axis accelerometer and a Dynamixel bus to interface with the robot’s servos.
I intend to use an alternative electronics based on a more powerful ARM computer plus several peripherals. For the main computer, my current choice is the ODROID-XU which is a quad Cortex-A15 1.6GHz CPU with 2GB RAM.
Instead of using a controller board, I’ll be using a USB2AX to interface the Dynamixel servos and I’ll use I2C components for the gyroscope and accelerometer.
On the picture are shown the components that I already got and that I’ll be testing:
- I2C 12 bit 4 channels ADC (ADS1015 chip)
- I2C voltage-level translator (PCA9306 chip)
- I2C 10DOF with 3-axis gyro, 3-axis accelerometer, 3-axis compass, temperature and pressure sensors (L3G4200D, ADXL345, HMC5883L, BMP085 chips)
- Force sensing resistor (.1N to 100N)
- ODROID USB IO Board with GPIO/PWM/SPI/UART/I2C/ADC interfaces
- USB2AX Dynamixel interface
I’ll be using the native I2C interface I2C_0 that is available in the LCD connector (CON15) in the back of the ODROID-XU (the schematics are available through a customer email request to Hardkernel).
The LCD connector is an IPEX 40 pin with 0.5mm pitch. I got some a couple of cables from Ebay, but now I saw that Hardkernel (the maker of the ODROID) is also selling the cable. The pin configuration that I’ll be using for the I2C interface is:
- 4 – 1.8V
- 6 – SCL
- 7 – SDA
- 10 – GND
The ODROID-XU’s I2C interface is rated at 1.8V, so I’ll be using the PCA9306 to translate it to the rest of the I2C components which are rated at a higher voltage.
The DARwIn-OP requires a gyroscope and an accelerometer, but I am interested also in using the compass and the force sensors (through the AD converter) for a future version of the DARwIn-OP feet.