H8S2111B Datasheet, PDF (441/582 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family / H8S/2100 Series

15.4.6 Host Interface Clock Start Request (CLKRUN)
A request to restart the clock (LCLK) can be sent to the host processor by means of the CLKRUN
pin. With LPC data transfer and SERIRQ in continuous mode, a clock restart is never requested
since the transfer cycles are initiated by the host. With SERIRQ in quiet mode, when a host
interrupt request is generated the CLKRUN signal is driven and a clock (LCLK) restart request is
sent to the host. The timing for this operation is shown in figure 15.7.
CLK
CLKRUN
1
2
3
4
5
6
Pull-up enable
Drive by the slave processor
Drive by the host processor
Figure 15.7 Clock Start Request Timing
Cases other than SERIRQ in quiet mode when clock restart is required must be handled with a
different protocol, using the PME signal, etc.
Rev. 1.00, 05/04, page 407 of 544