341
CHAPTER 20 UART/SIO
20.5.5
UART/SIO Serial Output Data Register (TDR0)
The UART/SIO serial output data register (TDR0) is used to output (transmit) serial data.
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UART/SIO Serial Output Data Register (TDR0)
Figure 20.5-6 shows the bit configuration of the UART/SIO serial output data register.
Figure 20.5-6 UART/SIO Serial Output Data Register (TDR0)
This register holds data to be transmitted. The register accepts a write when the transmission data register
empty (TDRE) bit contains "1". An attempt to write to the bit is ignored when the bit contains "0".
When this register is updated at writting complete the transmission data and TDRE=0 (without depending
on TXE of the UART/SIO serial mode control register is "1" or "0"), the transmission operation is
initialized by writing "0" to TXE, TDRE becomes "1", and the update of this register becomes possible.
Moreover, when "0" is written in TXE without the starting transmission (when the transmission data is
written in TDR, and it has not transmitted TXE to "1" yet), TCPL is not set in "1". The transmission data is
transferred to the shift register for the transmission, it is converted into the serial data, and it is transmitted
from the serial data output terminal.
When transmit data is written to the UART/SIO serial output data register (TDR0), the transmission data
register empty bit (TDRE) is set to "0". Upon completion of transfer of transmit data to the transmission
shift register, the transmission data register empty bit (TDRE) is set to "1", allowing the next piece of
transmit data to be written. At this time, an interrupt occurs if transmission data register empty interrupts
have been enabled. Write the next piece of transmit data when transmit data empty occurs or the transmit
data empty (TDRE) bit is set to "1".
When the character bit length (CBL1, 0) is set to shorter than 8 bits, the excess upper bits (beyond the set
bit length) are ignored.
Note:
The data in this register cannot be updated when TDRE in UART/SIO serial status data register is
"0".
When this register is updated at writting complete the transmission data and TDRE=0 (without
depending on TXE of the UART/SIO serial mode control register 2 is "1" or "0"), the transmission
operation is initialized by writing "0" to TXE, TDRE becomes "1", and the update of this register
becomes possible.
Moreover, when "0" is written in TXE without the starting transmission (when the transmission data is
written in TDR, and it has not transmitted TXE to "1" yet), TCPL is not set in "1". And, to change
data, please write it after making TDRE "1" once by writing TXE =0.
Address
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
Initial value
0059
H
TDR0
TD7
TD6
TD5
TD4
TD3
TD2
TD1
TD0
00000000
B
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W : Readable/writable (Read value is the same as write value)
Содержание F2 MC-8FX Family
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Страница 30: ...16 CHAPTER 1 DESCRIPTION 1 FPT 64P M23 FPT 64P M24 2 For the I O circuit type refer to 1 8 I O Circuit Type ...
Страница 34: ...20 CHAPTER 1 DESCRIPTION ...
Страница 35: ...21 CHAPTER 2 HANDLING DEVICES This chapter gives notes on using 2 1 Device Handling Precautions ...
Страница 38: ...24 CHAPTER 2 HANDLING DEVICES ...
Страница 39: ...25 CHAPTER 3 MEMORY SPACE This chapter describes memory space 3 1 Memory Space 3 2 Memory Map ...
Страница 43: ...29 CHAPTER 4 MEMORY ACCESS MODE This chapter describes the memory access mode 4 1 Memory Access Mode ...
Страница 56: ...42 CHAPTER 5 CPU ...
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Страница 105: ...91 CHAPTER 8 INTERRUPTS This chapter explains the interrupts 8 1 Interrupts ...
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Страница 536: ...522 CHAPTER 28 256 KBIT FLASH MEMORY ...
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Страница 564: ...550 CHAPTER 29 EXAMPLE OF SERIAL PROGRAMMING CONNECTION ...
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