H8S33 Datasheet, PDF (874/1489 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer

Section 17 Smart Card Interface
17.3.7 Operation in GSM Mode
Switching the Mode: When switching between smart card interface mode and software standby
mode, the following switching procedure should be followed in order to maintain the clock duty.
• 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 period.
During this interval, clock output is fixed at the specified level, with the duty preserved.
[5] Make the transition to the software standby state.
• When returning to smart card interface mode from software standby mode
[6] Exit the software standby state.
[7] Write 1 to the CKE0 bit in SCR and output the clock. Signal generation is started with the
normal duty.
Normal operation
Software
standby
Normal operation
[1] [2] [3]
[4] [5]
[6] [7]
Figure 17.9 Clock Halt and Restart Procedure
Rev. 5.00 Mar 28, 2005 page 810 of 1422
REJ09B0234-0500