SH7727 Datasheet, PDF (725/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 20 Serial IO (SIOF)
6. Transmit/receive reset execution
When using the SIOF again after a transmit/receive operation ends, or after erroneous
operation occurs, first execute a transmit reset (TXRST) or receive reset (RXRST).
7. Using the control data interface (slot position)
Loss of transmit or control data may occur if transmit and control data are mixed within a
single frame during a transmit operation in any of the following modes:
(1) Master mode with an external clock (SIOMCLK) used as the master clock
(2) Slave mode
Therefore, the control data interface (slot position) should be used under the following
conditions:
(1) Master mode
(2) Master clock: Peripheral clock (PCLK)
8. Serial IO (SIOF) reception operation
During serial IO (SIOF) operation, if reception is performed with a slot length of 8 bits and
LSB first, unwanted data is added at the start of the reception data, FIFO storage is delayed
one byte at a time, and the final portion of the data remains in the shift register. To prevent
this, use one of the three methods described below.
(1) Perform reception using a slot length of 8 bits and LSB first, and read and discard the
unwanted data.
Read and discard the unwanted data at the start of the reception data. Then, input a dummy
FS after the final portion of data so that the real final portion of data is stored in the FIFO.
This will ensure that reception operates correctly when a slot length of 8 bits and LSB first
is used.
(2) Perform reception using a slot length of 8 bits and MSB first, then use software processing
to convert the data to LSB-first format.
Data reception operates correctly when a slot length of 8 bits and MSB first is used. After
receiving the data in MSB-first format, use software processing to convert the data read
from the FIFO from MSB-first to LSB-first format. The result can then be used as 8-bit slot
length LSB-first data.
(3) Perform reception using a slot length of 16 bits and LSB first, and read only the required
data.
Data reception operates correctly when a slot length of 16 bits and LSB first is used. Then
one of the following two methods can be used to obtain data that can be used as 8-bit slot
length LSB-first data.
(a) Make settings on the transmitting side so that only the upper 8 bits are used for actual
data. Then, after the 16-bit data is received by the SH7727, extract the upper 8 bits and
use it as 8-bit slot length LSB-first data.
Rev. 5.00 Dec 12, 2005 page 653 of 1034
REJ09B0254-0500