SH7730 Datasheet, PDF (902/1188 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7780 Series

Section 25 SIM Card Module (SIM)
(4) Standby Mode (Clock Stop)
When switching between smart card interface mode and standby mode, in order to retain the clock
duty, the following switching procedure should be used. The switching procedure is shown in
figure 25.11.
• When switching from smart card interface mode to standby mode
(a) Write 0 to the TE and RE bits in the serial control register (SCSCR), to stop transmit and
receive operations. At the same time, set the CKE1 bit to the value for the output-fixed
state in standby mode.
(b) Write 0 to the CKE0 bit in SCSCR to stop the clock.
(c) Wait for one cycle of the serial clock. During this interval, the duty is retained, and the
clock output is fixed at the specified level.
(d) Make the transition to standby mode.
• To return from standby mode to smart card interface mode
(e) Cancel the standby state.
(f) Set the CKE1 bit in the serial control register (SCSCR) to the value of the output-fixed
state at the beginning of standby (the current SIM_CLK pin state).
(g) Write 1 to the CKE0 bit in SCSCR to output a clock signal. Clock signal generation begins
at normal duty.
Normal operation
Standby
mode
Normal operation
SIM_CLK
(a) (b) (c)
(d)
(e) (f) (g)
Figure 25.11 Procedure for Stopping Clock and Restarting
(5) Power-On and Clock Output
In order to retain the clock duty from power-on, the following switching procedure should be
used.
1. In order to fix the potential, a pull-up resistance/pull-down resistance is used.
2. Use the CKE1 bit in the serial control register (SCSCR) to fix the specified output.
3. Set the CKE0 bit in SCSCR to 1 to start clock output.
Rev. 1.00 Sep. 19, 2007 Page 854 of 1136
REJ09B0359-0100