Synchronous VME64x Block Transfers with Bus-Invert Coding For Low Noise, Low Power Performance

The VME64x standard defines a double edge source synchronous block transfer (2eSST) capable to sustain a data transfer rate up to 320 MByte/s on the VMEbus. This level of performance is achieved by double edge clocking a 64-bit bus with bursts of data strobe pulses. The switching activity of such a wide bus on a shared backplane challenges the signal integrity and the data transfer reliabitity. The Bus-Invert is a well known coding technique developed to lower the peak power dissipation in I/O busses by decreasing their switching activity. In this paper we discuss how the Bus-Invert coding can be applied to improve the 2eSST performance. The hardware overheads introduced by the encoding algorithm is discussed in the view of deployments in low-latency, real-time applications.