RL78/G15 CHAPTER 12 SERIAL ARRAY UNIT
R01UH0959EJ0110 Rev.1.10 Page 379 of 765
Mar 7, 2023
12.3.5 Serial data register mn (SDRmn)
The SDRmn is the transmit/receive data register (16 bits) of channel n.
Bits 8 to 0 (lower 9 bits) of SDR00 and SDR01 function as a transmit/receive buffer register, and bits 15 to 9 (higher 7
bits) are used as a register that sets the division ratio of the operation clock (f
MCK
).
If the CCSmn bit of serial mode register mn (SMRmn) is cleared to 0, the clock set by dividing the operation clock by bits
15 to 9 (higher 7 bits) of the SDRmn register is used as the transfer clock.
If the CCSmn bit of serial mode register mn (SMRmn) is set to 1, set bits 15 to 9 (upper 7 bits) of SDR00 and SDR01 to
0000000B. The input clock f
SCK
(slave transfer in simplified SPI or CSI mode) from the SCKp pin is used as the transfer
clock.
The lower 8 or 9 bits of the SDRmn register function as a transmit/receive buffer register. During reception, the parallel
data converted by the shift register is stored in the lower 8 or 9 bits, and during transmission, the data to be transmitted
to the shift register is set to the lower 8 or 9 bits.
The SDRmn register can be read or written in 16-bit units.
However, the higher 7 bits can only be written or read when the operation is stopped (SEmn = 0). During operation
(SEmn = 1), a value is written only to the lower 8 or 9 bits of the SDRmn register. When the SDRmn register is read
during operation, the higher 7 bits are always read as 0.
The value of each SDRmn register is 0000H following a reset.
Figure 12-7. Format of Serial Data Register mn (SDRmn)
Address: FFF10H, FFF11H (SDR00), FFF12H, FFF13H (SDR01) After reset: 0000H R/W
FFF11H (SDR00) FFF10H (SDR00)
Symbol 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
SDRmn
SDRmn[15:9] Transfer clock setting by dividing the operation clock
0 0 0 0 0 0 0 f
MCK
/2
0 0 0 0 0 0 1 f
MCK
/4
0 0 0 0 0 1 0 f
MCK
/6
0 0 0 0 0 1 1 f
MCK
/8
:
:
:
:
1 1 1 1 1 1 0 f
MCK
/254
1 1 1 1 1 1 1 f
MCK/
256
(Cautions and Remarks are listed on the next page.)