H8S2245 datasheet(539/818 Pages) RENESAS

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Section 13 Smart Card Interface

Rev.3.00 Mar. 26, 2007 Page 497 of 772

REJ09B0355-0300

When performing transfer using the DTC, it is essential to set and enable the DTC before carrying

out SCI setting. For details of the DTC setting procedures, see section 7, Data Transfer Controller

(DTC).

In a receive operation, an RXI interrupt request is generated when the RDRF flag in SSR is set to

1. If the RXI request is designated beforehand as a DTC activation source, the DTC will be

activated by the RXI request, and transfer of the receive data will be carried out. At this time, the

RDRF flag is cleared to 0 if DISEL in DTC is 0 and the transfer counter value is not 0. If DISEL

is 1, or if DISEL is 0 and the transfer counter value is 0, the DTC transfers the receive data but

does not clear the flag. Therefore, the flag should be cleared by the CPU. If an error occurs, an

error flag is set but the RDRF flag is not. Consequently, the DTC is not activated, but instead, an

ERI interrupt request is sent to the CPU. Therefore, the error flag should be cleared.

13.3.7

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.

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