![](http://datasheet.mmic.net.cn/30000/M30263F3AFP_datasheet_2358719/M30263F3AFP_153.png)
13. Serial I/O
page 136
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Figure 13.1.4. U0TB to U2TB registers, U0RB to U2RB registers, U0BRG to U2BRG registers
(b15)
b7
b0
(b8)
b7
b0
UARTi Transmit Buffer Register (i=0 to 2)(1)
Function
Transmit data
Nothing is assigned.
When write, set to "0". When read, its content is indeterminate.
Symbol
Address
After Reset
U0TB
03A316-03A216
Indeterminate
U1TB
03AB16-03AA16
Indeterminate
U2TB
037B16-037A16
Indeterminate
RW
NOTES:
1. Use MOV instruction to write to this register.
WO
b7
UARTi Baud Rate Generation Register (i=0 to 2)(1, 2, 3)
b0
Symbol
Address
After Reset
U0BRG
03A116
Indeterminate
U1BRG
03A916
Indeterminate
U2BRG
037916
Indeterminate
Function
Assuming that set value = n, UiBRG divides the count source
by n + 1
0016 to FF16
Setting Range
NOTES:
1. Write to this register while serial I/O is neither transmitting nor receiving.
2. Use MOV instruction to write to this register.
The transfer clock is shown below when the setting value in the UiBRG register is set as n.
(1) When the CKDIR bit in the UiMR register to “0” (internal clock)
Clock synchronous serial I/O mode
: fj/(2(n+1))
Clock asynchronous serial I/O (UART) mode
: fj/(16(n+1))
(2) When the CKDIR bit in the UiMR register to “1” (external clock)
Clock synchronous serial I/O mode
: fEXT
Clock asynchronous serial I/O (UART) mode
: fEXT/(16(n+1))
fj : f1SIO, f2SIO, f8SIO, f32SIO
fEXT : Input from CLKi pin
3. Set the UiBRG register after setting the CLK1 and CLK0 bits in the UiC0 registers.
RW
WO
NOTES:
1. When the SMD2 to SMD0 bits in the UiMR register are set to “000 2” (serial I/O disabled) or the RE bit in the UiC1 register is set to “0” (reception
disabled), all of the SUM, PER, FER and OER bits are set to “0” (no error). The SUM bit is set to “0” (no error) when all of the PER, FER and OER
bits are set to “0” (no error). Also, the PER and FER bits are set to “0” by reading the lower byte of the UiRB register.
2. The ABT bit is set to “0” by setting to “0” by program. (Writing “1” has no effect.)
Nothing is assigned at the bit 11 in the U0RB and U1RB registers. When write, set to "0". When read, its content is "0".
(b15)
Symbol
Address
After Reset
U0RB
03A716-03A616
Indeterminate
U1RB
03AF16-03AE16
Indeterminate
U2RB
037F16-037E16
Indeterminate
b7
b0
(b8)
b7
b0
UARTi Receive Buffer Register (i=0 to 2)
Function
Bit Name
Bit
Symbol
0 : No framing error
1 : Framing error found
0 : No parity error
1 : Parity error found
0 : No error
1 : Error found
OER
FER
PER
SUM
Overrun error flag (1)
Framing error flag (1)
Parity error flag (1)
Error sum flag (1)
0 : No overrun error
1 : Overrun error found
Receive data (D7 to D0)
ABT
Arbitration lost detecting
flag (2)
0 : Not detected
1 : Detected
RW
RO
(b7-b0)
(b10-b9)
Receive data (D 8)
(b8)
Nothing is assigned.
When write, set to "0". When read, its content is indeterminate.
RW
RO