Transmit End Flag - Philips CEM2100/00 Service Manual

xxxx
TD1BUF
***** 1
Shift register
TXD1 pin
UART1SR<TBEP>
INTTXD1 interrupt
Figure 12-9 Generation of Transmit Data Buffer Empty

12.9.6 Transmit End Flag

When data are transmitted and no data is in TD1BUF (UART1SR<TBEP> = "1"), transmit end flag
UART1SR<TEND> is set to "1". The UART1SR<TEND> is cleared to "0" when the data transmit is started
after writing the TD1BUF.
Shift register
TXD1 pin
UART1SR<TBEP>
UART1SR<TEND>
INTTXD1 interrupt
Figure 12-10 Generation of Transmit End Flag and Transmit Data Buffer Empty
Data write
yyyy
1xxxx0 * 1xxxx
Start Bit 0
1xx 1x ***** 1
****
***
Stop
Page 147
**** 1x ***** 1
Final bit Stop
Data write for TD1BUF
T5CL8
Data write
zzzz
1yyyy0
After reading UART1SR writing
TD1BUF clears TBEP.
* 1yyyy
1yyyy0
Bit 0
Start