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RL78/G1P
CHAPTER 11 SERIAL ARRAY UNIT
R01UH0895EJ0100 Rev.1.00
322
Nov 29, 2019
11.3.5 Higher 7 bits of the serial data register mn (SDRmn)
The SDRmn register is the transmit/receive data register (16 bits) of channel n.
Bits 8 to 0 (lower 9 bits) of SDR00, SDR01 function as a transmit/receive buffer register, and bits 15 to 9 are used as a
register that sets the division ratio of the operation clock (f
MCK
, f
SCK
).
If the CCSmn bit of serial mode register mn (SMRmn) is cleared to 0, the clock set by dividing the operating clock by
the 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 CSI mode) from the SCKp pin is used as the transfer clock.
The lower 8/9 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 9 bits, and during transmission, the data to be transmitted to the
shift register is set to the lower 9 bits.
The SDRmn register can be read or written in 16-bit units.
However, the higher 7 bits can be written or read only when the operation is stopped (SEmn = 0). During operation
(SEmn = 1), a value is written only to the lower 9 bits of the SDRmn register. When the SDRmn register is read during
operation, 0 is always read.
Reset signal generation clears the SDRmn register to 0000H.
Figure 11-7. Format of Serial Data Register mn (SDRmn)
Address: FFF10H, FFF11H (SDR00), FFF12H, FFF13H (SDR01) After reset: 0000H R/W
Symbol 15
14
13
12
11
10 9 8 7 6 5 4 3 2 1 0
SDRmn
0
SDRmn[15:9]
Transfer clock setting by dividing the operating clock (f
MCK
)
0 0 0 0 0 0 0
f
MCK
/2, f
SCK
/2 (in CSI slave)
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 1. Setting SDRmn[15:9] = (0000000B, 0000001B) is prohibited when UART is used.
2. Do not write eight bits to the lower eight bits if operation is stopped (SEmn = 0). (If these bits are
written to, the higher seven bits are cleared to 0.)
Remarks 1.
For the function of the lower 9 bits of the SDRmn register, see
11.2 Configuration of Serial Array Unit
.
2.
m: Unit number (m = 0), n: Channel number (n = 0, 1)
FFF11H (SDR00)
FFF10H (SDR00)