A tunable bus encoder for off-chip data buses

Off-Chip buses constitute a significant portion of the total system power in embedded systems. Past research has focused on encoding contiguous bit positions in data values to reduce the transition activity in the off-chip data buses. In this paper, we propose TUnable Bus Encoding (TUBE) scheme to reduce the power consumption in the data buses, which exploits repetition in contiguous as well as non-contiguous bit positions in order to encode data values. We also solve the problem of keeping just one control signal for our codec designWe compare our results with some of the already existing best schemes such as Frequent Value encoding (FVE) and FV-MSB-LSB encoding schemes. We find that our scheme achieves an improvement of 21% on average and up to 28% on some benchmarks over the FVE scheme and up to 84% over unencoded data. In comparison to FV-MSB-LSB encoding scheme, our scheme improves the energy savings by 10% on average and up to 21% for some media applications at the expense of minimal 0.45% performance overhead. We present a hardware design of our codec and provide a detailed analysis of the hardware overhead in terms of area, delay and energy consumption. We find that our codec can be easily implemented in an on-chip memory controller with small area requirement of 0.0521 mm 2