Section 16 Serial Communication Interface 3 (SCI3)
16.3
Register Descriptions
The SCI3 has the following registers for each channel.
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Receive shift register (RSR)
Receive data register (RDR)
Transmit shift register (TSR)
Transmit data register (TDR)
Serial mode register (SMR)
Serial control register 3 (SCR3)
Serial status register (SSR)
Bit rate register (BRR)
16.3.1
Receive Shift Register (RSR)
RSR is a shift register that is used to receive serial data input from the RxD pin and convert it into
parallel data. When one frame of data has been received, it is transferred to RDR automatically.
RSR cannot be directly accessed by the CPU.
16.3.2
Receive Data Register (RDR)
RDR is an 8-bit register that stores received data. When the SCI3 has received one frame of serial
data, it transfers the received serial data from RSR to RDR, where it is stored. After this, RSR is
receive-enabled. As RSR and RDR function as a double buffer in this way, continuous receive
operations are possible. After confirming that the RDRF bit in SSR is set to 1, read RDR only
once. RDR cannot be written to by the CPU. RDR is initialized to H'00.
16.3.3 Transmit Shift Register (TSR)
TSR is a shift register that transmits serial data. To perform serial data transmission, the SCI3 first
transfers transmit data from TDR to TSR automatically, then sends the data that starts from the
LSB to the TXD pin. TSR cannot be directly accessed by the CPU.
Rev. 3.00 Sep. 10, 2007 Page 289 of 528
REJ09B0216-0300
RENESAS [ RENESAS TECHNOLOGY CORP ]
