5 serial output data register (sodr) – FUJITSU Semiconductor Controller MB89950/950A User Manual
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CHAPTER 10 UART
10.4.5
Serial Output Data Register (SODR)
The serial output data register (SODR) is used to output (transmit) serial data.
■ Serial output data register (SODR)
Figure 10.4-6 shows the bit allocations of the serial output data register.
Figure 10.4-6 Serial output data register (SODR)
When transmission is enabled, writing transmit data to this register transfers the transmit data to the
transmit register. The transmit data is converted to serial in the transmit shift register and sent to the serial
data output pin (SO).
Writing transmit data to the SODR register sets the transmit data flag to "0". After the transmit data is
transferred to the transmit shift register, the transmit data flag is set to "1" and the SODR is ready for the
next data. If transmit interrupt request is enabled, interrupt occurs. Write next transmission data when
transmit data flag bit is set to "1". When the data length is set to 7 bits, bit 7 does not have meaning.
Address
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Initial value
0023
H
XXXXXXXX
B
W
W
W
W
W
W
W
W
W
: Write-only
X
: Indeterminate