Interrupts In Smart Card Interface Mode - Renesas H8SX/1650 Hardware Manual

Section 13 Serial Communication Interface (SCI)
13.8.2

Interrupts in Smart Card Interface Mode

Table 13.13 shows the interrupt sources in smart card interface mode. A transmit end (TEI)
interrupt request cannot be used in this mode.
Table 13.13 SCI Interrupt Sources
Name Interrupt Source
ERI Receive error or error
signal detection
RXI Receive data full
TXI Transmit data empty
Data transmission/reception using the DTC is also possible in smart card interface mode, similar
to in the normal SCI mode. In transmission, the TEND and TDRE flags in SSR are simultaneously
set to 1, thus generating a TXI interrupt. This activates the DTC by a TXI request thus allowing
transfer of transmit data if the TXI request is specified as a source of DTC activation beforehand.
The TDRE and TEND flags are automatically cleared to 0 at data transfer by the DTC. If an error
occurs, the SCI automatically re-transmits the same data. During re-transmission, the TEND flag
remains as 0, thus not activating the DTC. Therefore, the SCI and DTC automatically transmit the
specified number of bytes, including re-transmission in the case of error occurrence. However, the
ERS flag in SSR, which is set at error occurrence, is not automatically cleared; the ERS flag must
be cleared by previously setting the RIE bit in SCR to 1 to enable an ERI interrupt request to be
generated at error occurrence.
When transmitting/receiving data using the DTC, be sure to set and enable the DTC prior to
making SCI settings. For DTC settings, see section 7, Data Transfer Controller (DTC).
In reception, an RXI interrupt request is generated when the RDRF flag in SSR is set to 1. This
activates the DTC by an RXI request thus allowing transfer of receive data if the RXI request is
specified as a source of DTC activation beforehand. The RDRF flag is automatically cleared to 0
at data transfer by the DTC. If an error occurs, the RDRF flag is not set but the error flag is set.
Therefore, the DTC is not activated and an ERI interrupt request is issued to the CPU instead; the
error flag must be cleared.
Rev.2.00 Jun. 28, 2007 Page 518 of 666
REJ09B0311-0200
Interrupt Flag
ORER, PER, or ERS
RDRF
TDRE
DTC Activation
Not possible
Possible
Possible
Priority
High
Low