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7 serial status register (ssr) – Renesas H8S/2111B User Manual

Page 275

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Rev. 1.00, 05/04, page 241 of 544

12.3.7

Serial Status Register (SSR)

SSR is a register containing status flags of the SCI and multiprocessor bits for transfer. TDRE,
RDRF, ORER, PER, and FER can only be cleared.

Bit Bit

Name

Initial
Value R/W Description

7 TDRE

1 R/(W)*

Transmit Data Register Empty

Indicates whether TDR contains transmit data.

[Setting conditions]

• When the TE bit in SCR is 0
• When data is transferred from TDR to TSR and

TDR is ready for data write

[Clearing conditions]

• When 0 is written to TDRE after reading TDRE = 1

6 RDRF

0 R/(W)*

Receive Data Register Full

Indicates that receive data is stored in RDR.

[Setting condition]

• When serial reception ends normally and receive

data is transferred from RSR to RDR

[Clearing conditions]

• When 0 is written to RDRF after reading RDRF = 1

The RDRF flag is not affected and retains its previous
value when the RE bit in SCR is cleared to 0.

5 ORER

0 R/(W)* Overrun

Error

[Setting condition]

• When the next data is received while RDRF = 1

[Clearing condition]

• When 0 is written to ORER after reading ORER = 1

4 FER 0 R/(W)* Framing

Error

[Setting condition]

• When the stop bit is 0

[Clearing condition]

• When 0 is written to FER after reading FER = 1

In 2-stop-bit mode, only the first stop bit is checked.

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