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R01UH0336EJ0102 Rev.1.02
Page 1236 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 22 Synchronous/Asynchronous Serial Interface H (UARTH)
(15)
URTHnTX – UARTHn Transmit Data Register
This register is used to store data to be transmitted.
Data for transmission in the URTHnTX register are stored in the transmission
shift register in the data format specified for transmission.
This register corresponds to bits 7 to 0 in the URTHnETXW register.
7-bit transfers
If the data length has been specified as 7 bits (URTHnCTL1.URTHnCLG = 0),
the transmitted data stored in this register are transferred in accord with the
specified direction for transfer (MSB-first/LSB-first) as described below.
• If transmission is LSB-first (URTHnCTL1.URTHnSLD = 1), URTHnTX[6:0] is
transferred to the shift register.
• If transmission is MSB-first (URTHnCTL1.URTHnSLD = 0), URTHnTX[7:1]
is transferred to the shift register.
For details on data formats, refer to Section 22.6.1, Data Formats.
Access
This register can be read/written in 8-bit units.
Address
<URTHn_base1> + 2C
H
Initial value
FF
H
This register is initialized by a reset from any source.
When transmission and reception are enabled (URTHnCTL0.URTHnPW =
URTHnTXE = 1), writing to this register triggers the start of transmission.
Note
If the next data are written to this register before ongoing transmission is
completed, the interface will wait until the ongoing transmission is completed
and then transmit the next data. Continuous transmission is thus possible.
Caution
In the consecutive two-frame transfer, the receive data register is only
accessible in 16-bit units (URTHnTXHL). Do not write to this register in 8-bit
units.
7
6
5
4
3
2
1
0
URTHnTX[7:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Table 22-23
URTHnTX Register Contents
Bit Position
Bit Name
Function
7 to 0
URTHnTX
[7:0]
UARTHn transmit data (See Table 22-27, Accesses according to Transmission
Modes.)