Datasheet

Section 12 Serial Communication Interface
Rev.7.00 Dec. 24, 2008 Page 443 of 698
REJ09B0074-0700
12.10.6 Operation in Case of Mode Transition
• Transmission
Operation should be stopped (by clearing TE, TIE, and TEIE to 0) before making a module
stop mode, software standby mode, watch mode, subactive mode, or subsleep mode transition.
TSR, TDR, and SSR are reset. The output pin states in module stop mode, software standby
mode, watch mode, subactive mode, or subsleep mode depend on the port settings, and
becomes high-level output after the relevant mode is cleared. If a transition is made during
transmission, the data being transmitted will be undefined. When transmitting without
changing the transmit mode after the relevant mode is cleared, transmission can be started by
setting TE to 1 again, and performing the following sequence:
SSR read -> TDR write -> TDRE clearance. To transmit with a different transmit mode after
clearing the relevant mode, the procedure must be started again from initialization. Figure
12.39 shows a sample flowchart for mode transition during transmission. Port pin states are
shown in figures 12.40 and 12.41.