HD6432351 datasheet(670/1025 Pages) RENESAS

670 / 1025 page

Section 14 Smart Card Interface

Rev. 3.00 Sep 15, 2006 page 636 of 988

REJ09B0330-0300

14.3.7

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] Write H'00 to SMR and SCMR.

[6] Make the transition to the software standby state.

• When returning to smart card interface mode from software standby mode:

[7] Exit the software standby state.

[8] Set the CKE1 bit in SCR to the value for the fixed output state (current SCK pin state) when

software standby mode is initiated.

[9] Set smart card interface mode and output the clock. Signal generation is started with the

normal duty.

[1] [2] [3]

[4] [5] [6]

[7] [8] [9]

Software

standby

Normal operation

Figure 14.9 Clock Halt and Restart Procedure

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