17 I2C MASTER (I2CM)
S1C17554/564 TECHNICAL MANUAL
Seiko Epson Corporation
17-9
I2C Master Data Register (I2CM_DAT)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
I2C Master Data
Register
(I2CM_DAT)
0x4344
(16 bits)
D15–12 –
reserved
–
0 when being read.
D11
RBRDY
Receive buffer ready flag
1 Ready
0 Empty
0
R
D10
RXE
Receive execution
1 Receive
0 Ignored
0
R/W
D9
TXE
Transmit execution
1 Transmit
0 Ignored
0
R/W
D8
RTACK
Receive/transmit ACK
1 Error
0 ACK
0
R/W
D7–0 RTDT[7:0]
Receive/transmit data
RTDT7 = MSB
RTDT0 = LSB
0x0 to 0xff
0x0 R/W
D[15:12] Reserved
D11
RBRDY: Receive Buffer Ready Flag Bit
Indicates the receive buffer status.
1 (R):
Receive data exists
0 (R):
No receive data (default)
The RBRDY flag becomes 1 when the data received in the shift register is loaded to RTDT[7:0] and
reverts to 0 when the receive data is read out from RTDT[7:0]. Interrupts can also be generated once the
flag value becomes 1.
D10
RXE: Receive Execution Bit
Receives 1 byte of data.
1 (R/W): Data reception start
0 (R/W): Ineffective (default)
Setting RXE to 1 and TXE to 0 starts receiving for 1 byte of data. RXE can be set to 1 for subsequent re-
ception, even if the slave address is being sent or data is being received. RXE is reset to 0 as soon as D6
is loaded to the shift register.
D9
TXE: Transmit Execution Bit
Transmits 1 byte of data.
1 (R/W): Data transmission start
0 (R/W): Ineffective (default)
Transmission is started by setting the transmit data to RTDT[7:0] and writing 1 to TXE. TXE can be
set to 1 for subsequent transmission, even if the slave address or data is being sent. TXE is reset to 0 as
soon as the data set in RTDT[7:0] is transferred to the shift register.
D8
RTACK: Receive/Transmit ACK Bit
When transmitting data
Indicates the response bit status.
1 (R/W): Error (NAK)
0 (R/W): ACK (default)
RTACK becomes 0 when ACK is returned from the slave after 1 byte of data is sent, indicating that the
slave has received the data correctly. If RTACK is 1, the slave device is not operating or the data was
not received correctly.
When receiving data
Sets the response bit sent to the slave.
1 (R/W): Error (NAK)
0 (R/W): ACK (default)
To return an ACK after data has been received, RTACK should be set to 0 before the I2CM module
sends the response bit. To return a NAK, set RTACK to 1.