To update data in DPM substantially at the same rate with a clock frequency of a dual port memory.
A comparator comprises an updating element in which a first port is used as output connected to the input of an updating element in a first clock, and a second port is used as input connected to the output of the updating element in a second clock, and a next address is accessed through the first port in the second clock, first input connected to the output of ADC in order to receive parameter values in the first clock, second input which receives the next receiving parameter values in the second clock, and output which supplies a match signal. The comparator enables the first port to be used as the input in the second clock by using the match signal. The data updated with the updating element in the first clock is supplied not in the second port but in the first port. They are supplied correctly in the input of the updating element in the second clock.
Arihara Koichi
Matsushima Tetsuo