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A Study on a Multi-keypad Circuit Design of Robot Controllers

This paper presented a method of design of multi-keypad which supports sensing of any multi key pressing. Traditionally, 4x4 keypad used in many applications has not been supported for multi-pressing, so some key pressing combinations could not be identified. Because user could not know the special key pressing, so keypad circuit design has been hidden issues between the hardware engineer and software engineer. If hardware designer do not consider the power dissipation when designing keypad circuit, CPU or other parts of circuits could be hot if pressed long time, so MCU (Microcontroller Unit) could be broken after some time, and naturally it would spends many power of mobile devices. Some circuits could make big noise to CPU, so they could not always sense the same way as designed. Noise signals caused by capacitance of forward biased diode could make the sensing speed slower and excessive sensing voltage. To support multi-keypad sensing, special keypad circuit has been developed to solve every key sensing problems, battery consumption, and noise problems. To verify the effectiveness of sensing of multi-keypad, testing program was developed with Atmel AVR, Renesas RL78, and Cortex-M3 ARM MCU of STMicroelectronics. With this circuit and testing program, special multi-keypad circuit proved to sense every key combination, minimized noise, and low power consumption. This was precisely intended for multi keypad in noisy and harsh environments between robot and its controllers. The “Multi-keypad” was tested successfully to prove its applicability with testing program.