Operation In Watch Mode; Switching Between System Clock And Sub Clock - Renesas H8S/2100 Series Hardware Manual

In case of reading more bytes than the number that has been received, (number of received bytes +
1) of data are always read out from the FIFO.
Reception of more than 18 bytes by the FIFO structure for this CIR module leads to an overrun.
When an overrun occurs, only values up to the 18th byte to have been received are read out in
response to the reading of more than 18 bytes.
16.4.3

Operation in Watch Mode

Initiate the transition to watch mode after making the below settings for the mode transition.
• Select the subclock (φsub) as the operating clock for the CIR module.
• Enable the CIR header-detected interrupt.
For a transition from watch mode to high-speed mode, the CIR module generates an interrupt on
detection of a received header, in accord with the settings before the transition.
The module is released from watch mode when the interrupt is generated, and makes the transition
to the high- or medium-speed mode.
16.4.4

Switching between System Clock and Sub Clock

If the operating clock is switched from the system clock to the subclock (φsub) while the CIR
module is operating, operation may not proceed correctly. To switch the operating clock, be sure
to stop the CIR module (by clearing the CIRE bit) beforehand.
Section 16 CIR Interface
Rev. 1.00 Apr. 28, 2008 Page 487 of 994
REJ09B0452-0100