HD6432351 datasheet(669/1025 Pages) RENESAS

669 / 1025 page

Section 14 Smart Card Interface

Rev. 3.00 Sep 15, 2006 page 635 of 988

REJ09B0330-0300

Data Transfer Operation by DMAC or DTC

In smart card mode, as with the normal SCI, transfer can be carried out using the DMAC or DTC.

In a transmit operation, the TDRE flag is also set to 1 at the same time as the TEND flag in SSR,

and a TXI interrupt is generated. If the TXI request is designated beforehand as a DMAC or DTC

activation source, the DMAC or DTC will be activated by the TXI request, and transfer of the

transmit data will be carried out. The TDRE and TEND flags are automatically cleared to 0 when

data transfer is performed by the DMAC or DTC. In the event of an error, the SCI retransmits the

same data automatically. The TEND flag remains cleared to 0 during this time, and the DMAC is

not activated. Thus, the number of bytes specified by the SCI and DMAC are transmitted

automatically even in retransmission following an error. However, the ERS flag is not cleared

automatically when an error occurs, and so the RIE bit should be set to 1 beforehand so that an

ERI request will be generated in the event of an error, and the ERS flag will be cleared.

When performing transfer using the DMAC or DTC, it is essential to set and enable the DMAC or

DTC before carrying out SCI setting. For details of the DMAC and DTC setting procedures, see

section 7, DMA Controller (DMAC), and section 8, 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 DMAC or DTC activation source, the DMAC

or DTC will be activated by the RXI request, and transfer of the receive data will be carried out.

The RDRF flag is cleared to 0 automatically when data transfer is performed by the DMAC or

DTC. If an error occurs, an error flag is set but the RDRF flag is not. Consequently, the DMAC or

DTC is not activated, but instead, an ERI interrupt request is sent to the CPU. Therefore, the error

flag should be cleared.

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