Renesas H8S/2100 Series, Hardware Manual

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Section 15 Serial Communication Interface (SCI)
Rev. 1.00 Apr. 28, 2008 Page 451 of 994
REJ09B0452-0100
For the direct convention type, logic levels 1 and 0 correspond to states Z and A, respectively, and
data is transferred with LSB-first as the start character, as shown in figure 15.23. Therefore, data
in the start character in the figure is H'3B. When using the direct convention type, write 0 to both
the SDIR and SINV bits in SCMR. Write 0 to the O/
E
bit in SMR in order to use even parity,
which is prescribed by the smart card standard.
Ds
A Z Z A A A Z A A A (Z) (Z) state
D7 D6 D5 D4 D3 D2 D1 D0 Dp
Figure 15.24 Inverse Convention (SDIR = SINV = O/
E
= 1)
For the inverse convention type, logic levels 1 and 0 correspond to states A and Z, respectively
and data is transferred with MSB-first as the start character, as shown in figure 15.24. Therefore,
data in the start character in the figure is H'3F. When using the inverse convention type, write 1 to
both the SDIR and SINV bits in SCMR. The parity bit is logic level 0 to produce even parity,
which is prescribed by the smart card standard, and corresponds to state Z. Since the SINV bit of
this LSI only inverts data bits D7 to D0, write 1 to the O/
E
bit in SMR to invert the parity bit in
both transmission and reception.
15.7.3 Block Transfer Mode
Block transfer mode is different from normal smart card interface mode in the following respects.
•
If a parity error is detected during reception, no error signal is output. Since the PER bit in
SSR is set by error detection, clear the bit before receiving the parity bit of the next frame.
•
During transmission, at least 1 etu is secured as a guard time after the end of the parity bit
before the start of the next frame.
•
Since the same data is not re-transmitted during transmission, the TEND flag in SSR is set
11.5 etu after transmission start.
•
Although the ERS flag in block transfer mode displays the error signal status as in normal
smart card interface mode, the flag is always read as 0 because no error signal is transferred.