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CHAPTER 3 FUNCTIONAL DESCRIPTION
User’s Manual S14054EJ4V0UM
47
Figure 3-10 shows a timing example of changing the port by inputting the SKIP signal while the port is read.
In this case, the new port is selected two clocks of FCLK after the SKIP signal has been detected. The
µ
PD98431 outputs valid receive data for the duration of two clocks, until the new port is selected. If data is
read from the port that has been skipped by the SKIP signal (if readable receive data does not exist in any
other port), the original port is indicated by RXFPT[2:0] two clocks after the valid data of two clocks (refer to
Figure 3-10 (b)
and
(d)
). Because the
µ
PD98431 is in IDLE status when the next port is indicated after the
SKIP signal has been input, inputting the PASS signal is necessary for starting to read.
If the port that has been skipped by the SKIP signal is selected again, the port starts outputting receive data
next to the one that was output last when the port was skipped. By using the SKIP signal, therefore, the data
received by each port can be divided into blocks and read. Determine a unit in which data is to be divided
and read, and input the SKIP signal in that unit until the data end attribute appears on the RXFDQ or FDQ
signal. In this way, each port can be successively read in units of reading. Unlike writing data to the transmit
FIFO, however, the
µ
PD98431 specifies a port to be read.
Do not input the SKIP signal and the PASS signal for the duration of two or more clocks. To skip a port by
inputting the SKIP signal two times or more, confirm that a new port is selected after the first SKIP signal has
been input for the duration of one clock, and then input the next SKIP clock.
Содержание mPD98431
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