SH7059 Datasheet, PDF (453/1042 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

15. Serial Communication Interface (SCI)
• Bit 7—Transmit Data Register Empty (TDRE): Indicates that the SCI has loaded transmit data from TDR into TSR
and new serial transmit data can be written in TDR.
Bit 7: TDRE
0
Description
TDR contains valid transmit data
[Clearing conditions]
• When 0 is written to TDRE after reading TDRE = 1
• When the DMAC writes data in TDR
1
TDR does not contain valid transmit data
(Initial value)
[Setting conditions]
• Power-on reset, hardware standby mode, or software standby mode
• When the TE bit in SCR is 0
• When data is transferred from TDR to TSR, enabling new data to be written in TDR
• Bit 6—Receive Data Register Full (RDRF): Indicates that RDR contains received data.
Bit 6: RDRF
0
Description
RDR does not contain valid receive data
[Clearing conditions]
• Power-on reset, hardware standby mode, or software standby mode
• When 0 is written to RDRF after reading RDRF = 1
• When the DMAC reads data from RDR
(Initial value)
1
RDR contains valid received data
[Setting condition]
RDRF is set to 1 when serial data is received normally and transferred from RSR to RDR
Note: RDR and RDRF are not affected by detection of receive errors or by clearing of the RE bit to 0 in the serial control
register. They retain their previous contents. If RDRF is still set to 1 when reception of the next data ends, an
overrun error (ORER) occurs and the receive data is lost.
• Bit 5—Overrun Error (ORER): Indicates that data reception ended abnormally due to an overrun error.
Bit 5: ORER
0
1
Description
Receiving is in progress or has ended normally
(Initial value)
Clearing the RE bit to 0 in the serial control register does not affect the ORER bit, which
retains its previous value.
[Clearing conditions]
• Power-on reset, hardware standby mode, or software standby mode
• When 0 is written to ORER after reading ORER = 1
A receive overrun error occurred
RDR continues to hold the data received before the overrun error, so subsequent receive
data is lost. Serial receiving cannot continue while ORER is set to 1. In synchronous mode,
serial transmitting is disabled.
[Setting condition]
ORER is set to 1 if reception of the next serial data ends when RDRF is set to 1
Rev.3.00 Mar. 12, 2008 Page 363 of 948
REJ09B0177-0300