3069RF-ZTAT Datasheet, PDF (556/1003 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER

Switching Modes: When switching from receive mode to transmit mode, first confirm that the
receive operation has been completed, then start from initialization, clearing RE to 0 and setting
TE to 1. The RDRF, PER, or ORER flag can be used to check that the receive operation has been
completed.
When switching from transmit mode to receive mode, first confirm that the transmit operation has
been completed, then start from initialization, clearing TE to 0 and setting RE to 1. The TEND
flag can be used to check that the transmit operation has been completed.
Fixing Clock Output: When the GM bit is set to 1 in SMR, clock output can be fixed by means
of the CKE1 and CKE0 bits in SCR. The minimum clock pulse width can be set to the specified
width in this case.
Figure 14.9 shows the timing for fixing clock output. In this example, GM = 1, CKE1 = 0, and the
CKE0 bit is controlled.
SCK
Specified pulse
width
CKE1 value
Specified pulse
width
SCR write
(CKE0 = 0)
SCR write
(CKE0 = 1)
Figure 14.9 Timing for Fixing Cock Output
Interrupt Operations: The smart card interface has three interrupt sources: transmit-data-empty
(TXI), transmit/receive-error (ERI), and receive-data-full (RXI). The transmit-end interrupt
request (TEI) is not available in smart card mode.
A TXI interrupt is requested when the TEND flag is set to 1 in SSR. An RXI interrupt is requested
when the RDRF flag is set to 1 in SSR. An ERI interrupt is requested when the ORER, PER, or
ERS flag is set to 1 in SSR. These relationships are shown in table 14.8.
Rev. 5.0, 09/04, page 534 of 978