Rev. 3.0, 10/02, page 362 of 686
13.3.2
Receive Data Register (RDR)
RDR is an 8-bit register that stores received data. When the SCI has received one byte 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.
13.3.3
Transmit Data Register (TDR)
TDR is an 8-bit register that stores data for transmission. When the SCI detects that TSR is empty,
it transfers the transmit data written in TDR to TSR and starts transmission. The double-buffered
structure of TDR and TSR enables continuous serial transmission. If the next transmit data has
already been written to TDR during serial transmission, the SCI transfers the written data to TSR
to continue transmission. Although TDR can be read from or written to by the CPU at all times, to
achieve reliable serial transmission, write transmit data to TDR only once after confirming that the
TDRE bit in SSR is set to 1.
13.3.4
Transmit Shift Register (TSR)
TSR is a shift register that transmits serial data. To perform serial data transmission, the SCI first
transfers transmit data from TDR to TSR, then sends the data to the TxD pin. TSR cannot be
directly accessed by the CPU.
Summary of Contents for H8S/2215 Series
Page 4: ...Rev 3 0 10 02 page iv of lviii ...
Page 6: ...Rev 3 0 10 02 page vi of lviii ...
Page 28: ...Rev 3 0 10 02 page xxviii of lviii ...
Page 122: ...Rev 3 0 10 02 page 64 of 686 ...
Page 132: ...Rev 3 0 10 02 page 74 of 686 ...
Page 156: ...Rev 3 0 10 02 page 98 of 686 ...
Page 198: ...Rev 3 0 10 02 page 140 of 686 ...
Page 320: ...Rev 3 0 10 02 page 262 of 686 ...
Page 384: ...Rev 3 0 10 02 page 326 of 686 ...
Page 474: ...Rev 3 0 10 02 page 416 of 686 ...
Page 608: ...Rev 3 0 10 02 page 550 of 686 ...
Page 614: ...Rev 3 0 10 02 page 556 of 686 ...
Page 650: ...Rev 3 0 10 02 page 592 of 686 ...
Page 652: ...Rev 3 0 10 02 page 594 of 686 ...
Page 680: ...Rev 3 0 10 02 page 622 of 686 ...
Page 732: ...Rev 3 0 10 02 page 674 of 686 ...
Page 740: ...Rev 3 0 10 02 page 682 of 686 ...