Development of a 35Mbps Asynchronous Bus Based Communication System for Tactile Sensors

Abstract

We have been developing a bus networked tactile sensor system using integrated devices with MEMS force sensors and signal processing LSIs (sensor nodes) to realize the whole body tactile sensation of humanoid robots. Although the MEMS-CMOS integration technology enables the MEMS sensor to have a digital serial communication function which can reduce the number of wires and transferred data, a channel capacity of the bus line is one of the factors to determine the scalability of the system and time resolution of the tactile data. High-speed data transmission of the whole system is a promising way to increase the channel capacity. We developed the 45MHz sensor nodes (previously 1.2MHz). In this paper, we report for the high channel capacity a high-speed asynchronous serial interface system and physical implementation. The interface was implemented on a generic Field Programmable Gate Array (FPGA) with an 800MHz oversampling based clock and data recovery, which uses a phase-shifted multi clocks (200MHz base clock and 4 phases of it). The developed system confirmed that at maximum 35Mbps bus channel capacity with about 550kHz sensor node packet generation rate can be realized, that means each of 255 sensor nodes on the bus can respond within 1ms on an average.