VEXnet Key 2.0
andre.lipke
Entry ID #: 2090
Created: Sun, Jan 10, 2016 6:01 PM
The device I selected is the VEXnet Key 2.0 which is the device used for radio communication between the VEX ARM® Cortex®-based Microcontroller and the VEXnet Joystick. I selected this because of its crucial part in VEX Robotics competitions and because of previous knowledge of how the system worked. The main component of the key is a CC2544 SoC (System on Chip) from Texas Instruments, a microprocessor with 32kb of RAM, USB, SPI, UART and includes a 2.4Ghz radio. The second to largest chip is a CC2591 range extender from Texas Instruments which boosts the range of the wireless signal. One of the interesting parts are the six debug terminals at the top. These terminals are used to download firmware once the board is put together and also debugging while the keys are running. Using a digital multimeter I found out the square terminal (bottom right) is ground, the one above it is 3.3V from the CC2544's internal voltage regulator and the rest are for data presumably a JTAG or SPI interface. With the CC2544's USB functionality, fast AES encryption and the CC2591's range boost, robots using the keys can maintain a reliable and secure connection to their paired joystick even with a lot of noise in the 2.4Ghz radio bands which is a must for competitions.
