Datasheet

Section 15 Serial Communication Interface (SCI, IrDA)
Page 934 of 1408 R01UH0309EJ0500 Rev. 5.00
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
When Changing from Smart Card Interface Mode to Software Standby Mode:
1. Set the data register (DR) and data direction register (DDR) corresponding to the SCK pin to
the value for the fixed output state in software standby mode.
2. Write 0 to the TE bit and RE bit in the serial control register (SCR) to halt transmit/receive
operation. At the same time, set the CKE1 bit to the value for the fixed output state in software
standby mode.
3. Write 0 to the CKE0 bit in SCR to halt the clock.
4. Wait for one serial clock cycle.
During this interval, clock output is fixed at the specified level, with the duty cycle preserved.
5. Make the transition to the software standby state.
When Returning to Smart Card Interface Mode from Software Standby Mode:
1. Exit the software standby state.
2. Write 1 to the CKE0 bit in SCR and output the clock. Signal generation is started with the
normal duty cycle.
[1] [2] [3] [4] [5] [7]
Software
standby
Normal operation Normal operation
[6]
Figure 15.32 Clock Halt and Restart Procedure