HD64F3048VTF8 Datasheet, PDF (565/903 Pages) Renesas Technology Corp – Hardware Manual Renesas 8-Bit Single-Chip

Section 14 Smart Card Interface
Examples of Operation in GSM Mode
When switching between smart card interface mode and software standby mode, use the following
procedures to maintain the clock duty cycle.
• Switching from smart card interface mode to software standby mode
1. Set the P9₄ data register (DR) and data direction register (DDR) to the values for the fixed
output state in software standby mode.
2. Write 0 to the TE and RE bits in the serial control register (SCR) to stop transmit/receive
operations. 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 stop the clock.
4. Wait for one serial clock cycle. During this period, the duty cycle is preserved and clock
output is fixed at the specified level.
5. Write H'00 to the serial mode register (SMR) and smart card mode register (SCMR).
6. Make the transition to the software standby state.
• Returning from software standby mode to smart card interface mode
1. Clear the software standby state.
2. Set the CKE1 bit in SCR to the value for the fixed output state at the start of software
standby (the current P9₄ pin state).
3. Set smart card interface mode and output the clock. Clock signal generation is started with
the normal duty cycle.
Normal operation
Software standby
mode
Normal operation
(1)(2)(3)
(4) (5)(6)
(1) (2)(3)
Figure 14.9 Procedure for Stopping and Restarting the Clock
Rev. 3.00 Sep 27, 2006 page 537 of 872
REJ09B0325-0300