tmp86c809ng TOSHIBA Semiconductor CORPORATION, tmp86c809ng Datasheet - Page 118

• Manufacturer Part Number: tmp86c809ng
• Description: 8 Bit Microcontroller Tlcs-870/c Series
• Manufacturer: TOSHIBA Semiconductor CORPORATION

10.9 Status Flag
10.9.4 Receive Data Buffer Full
10.9.5 Transmit Data Buffer Empty
RXD pin
RDBUF
UARTSR<RBFL>
INTRXD interrupt
Shift register
UARTSR<RBFL> is cleared to “0” when the RDBUF is read after reading the UARTSR.
are transferred to the transmit shift register and data transmit starts, transmit data buffer empty flag
UARTSR<TBEP> is set to “1”. The UARTSR<TBEP> is cleared to “0” when the TDBUF is written after
reading the UARTSR.
UARTSR<RBFL>
RXD pin
RDBUF
UARTSR<OERR>
INTRXD interrupt
Shift register
Note:Receive operations are disabled until the overrun error flag UARTSR<OERR> is cleared.
Loading the received data in RDBUF sets receive data buffer full flag UARTSR<RBFL> to "1". The
Note:If the overrun error flag UARTSR<OERR> is set during the period between reading the UARTSR and reading
When no data is in the transmit buffer TDBUF, UARTSR<TBEP> is set to “1”, that is, when data in TDBUF
the RDBUF, it cannot be cleared by only reading the RDBUF. Therefore, after reading the RDBUF, read the
UARTSR again to check whether or not the overrun error flag which should have been cleared still remains
set.
Figure 10-8 Generation of Receive Data Buffer Full
Figure 10-7 Generation of Overrun Error
xxx0 **
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xxx0 **
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Final bit
Final bit
Page 108
xxxx0
xxxx0
*
*
Stop
Stop
1xxxx0
xxxx
1xxxx0
After reading UARTSR then
RDBUF clears RBFL.
After reading UARTSR then
RDBUF clears OERR.
TMP86C809NG