Section 13 Serial Communication Interface (SCI)
Rev. 1.00 Mar. 12, 2008 Page 433 of 1178
REJ09B0403-0100
13.3.1
Receive Shift Register (RSR)
RSR is a shift register used to receive serial data that converts 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.
13.3.2
Receive Data Register (RDR)
RDR is an 8-bit register that stores receive data. When the SCI has received one frame of serial
data, it transfers the received serial data from RSR to RDR where it is stored. After this, RSR can
receive the next data. Since RSR and RDR function as a double buffer in this way, continuous
receive operations be performed. After confirming that the RDRF bit in SSR is set to 1, read RDR
for 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 transmit data. When the SCI detects that TSR is empty, it
transfers the transmit data written in TDR to TSR and starts transmission. The double-buffered
structures of TDR and TSR enables continuous serial transmission. If the next transmit data has
already been written to TDR when one frame of data is transmitted, 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 for 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 Family
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Page 552: ...Section 14 CRC Operation Circuit CRC Rev 1 00 Mar 12 2008 Page 504 of 1178 REJ09B0403 0100...
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Page 804: ...Section 19 LPC Interface LPC Rev 1 00 Mar 12 2008 Page 756 of 1178 REJ09B0403 0100...
Page 838: ...Section 20 Ethernet Controller EtherC Rev 1 00 Mar 12 2008 Page 790 of 1178 REJ09B0403 0100...
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Page 1066: ...Section 25 Flash Memory Rev 1 00 Mar 12 2008 Page 1018 of 1178 REJ09B0403 0100...
Page 1098: ...Section 26 Boundary Scan JTAG Rev 1 00 Mar 12 2008 Page 1050 of 1178 REJ09B0403 0100...
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