tmp89fm42 TOSHIBA Semiconductor CORPORATION, tmp89fm42 Datasheet - Page 228

• Manufacturer Part Number: tmp89fm42
• Description: 8 Bit Microcontroller
• Manufacturer: TOSHIBA Semiconductor CORPORATION

ters from Being Changed
16.4 Protection to Prevent UART0CR1 and UART0CR2 Regis-
16. Asynchronous Serial Interface (UART)
RA001
16.4 Protection to Prevent UART0CR1 and UART0CR2 Registers from Being
settings (for example, stop bit and parity) are not changed accidentally during the UART operation.
write instruction is executed on the register when it is protected from being changed, the bits remain unchanged and
keep their previous values.
Changed
The TMP89FM42 has a function that protects the registers from being changed so that the UART communication
Specific bits of UART0CR1 and UART0CR2 can be changed only under the conditions shown in Table 16-3. If a
Table 16-3 Changing of UART0CR1 and UART0CR2
UART0CR1<IRDASEL>
UART0CR1<STOPBT>
UART0CR2<STOPBR>
UART0CR2<RXDNC>
UART0CR2<RTSEL>
UART0CR1<EVEN>
UART0CR1<BRG>
Bit to be changed
UART0CR1<PE>
Selection of RXD pin input
Transfer base clock selec-
Selection of number of RT
TXD pin output selection
Transmit stop bit length
Receive stop bit length
noise rejection time
Parity selection
Parity addition
Function
clocks
tion
Page 214
UART0CR1
<TXE>
Both of these bits are "0"
Both of these bits are "0"
-
Conditions that allow the bit to be changed
UART0SR
<TBSY>
All of these bits are "0"
All of these bits are "0"
-
UART0CR1
<RXE>
Both of these bits are "0"
-
-
UART0SR
<RBSY>
-
-
TMP89FM42