1. CMSIS—cortex microcontroller software interface standard—ARM.
http://www.arm.com/products/processors/cortex-m/cortex-microcontroller-software-interface-standard.php
2. Cortex-m4 processor—ARM.
http://www.arm.com/products/processors/cortex-m/cortex-m4-processor.php
3. FreeRTOS—market leading RTOS (real time operating system) for embedded systems with internet of things extensions.
http://www.freertos.org/
4. Kalmegh, S., Samra, D., Rasegaonkar, N.: Obstacle avoidance for a mobile exploration robot using a single ultrasonic range sensor. In: Proceedings of 2010 International Conference on Emerging Trends in Robotics and Communication Technologies (INTERACT), pp. 8–11 (2010)
5. Kim, S., Kim, H.B.: High resolution mobile robot obstacle detection using low directivity ultrasonic sensor ring. In: Huang, D.S., Zhang, X., Garca, C.A.R., Zhang, L. (eds.) Advanced Intelligent Computing Theories and Applications. With Aspects of Artificial Intelligence, pp. 426–433. No. 6216 in Lecture Notes in Computer Science, Springer, Berlin Heidelberg (2011).
http://link.springer.com/chapter/10.1007/978-3-642-14932-0_53