Epson S1C17704 Technical Manual page 298

2
20 I C
D[7:0] RTDT[7:0]: Receive/Transmit Data Bits
In data transmission
Set a transmit data in this register. (Default: 0x0)
Data transmission begins when TXE (D9) is set to 1. If a slave address or data is being transmitted, a
new transmission starts after the current transmission has completed. The serial-converted data is output
from the SDA pin beginning with the MSB, in which the bits set to 0 are output as low-level signals.
When the data set in this register is transferred to the shift register, a cause of transmit buffer empty
interrupt occurs. The next transmit data can be written to the register after that.
In data reception
The received data can be read from this register. (Default: 0x0)
Data reception begins when RXE (D10) is set to 1. If a slave address is being transmitted or data
is being received, a new reception starts after the current reception has completed. When a receive
operation is completed and the data received in the shift register is loaded to this register, the RBRDY
flag (D11) is set and a cause of receive buffer full interrupt occurs. Thereafter, the data can be read out
at any time before a receive operation for the next data is completed. If the next data receive operation
is completed before this register is read out, the data in it is overwritten with the newly received data.
The serial data input from the SDA pin is converted into parallel data beginning with the MSB, with the
high-level signals changed to 1s and the low-level signals changed to 0s. The resulting data is stored in
this register.
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EPSON
S1C17704 TECHNICAL MANUAL