14 I
2
C (I2C)
14-20
Seiko Epson Corporation
S1C17M20/M21/M22/M23/M24/M25
TECHNICAL MANUAL (Rev. 1.0)
Note
: If the
I2CnCTL.MODEN bit is altered from 1 to 0 while sending/receiving data, the data be-
ing sent/received cannot be guaranteed. When setting the I2CnCTL.MODEN bit to 1 again
after that, be sure to write 1 to the I2CnCTL.SFTRST bit as well.
I2C Ch.
n
Transmit Data Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
I2CnTXD
15–8 –
0x00
–
R
–
7–0 TXD[7:0]
0x00
H0
R/W
Bits 15–8 Reserved
Bits 7–0
TXD[7:0]
Data can be written to the transmit data buffer through these bits. Make sure the I2C
n
INTF.TBEIF bit
is set to 1 before writing data.
Note: Be sure to avoid writing to the I2CnTXD register when the I2CnINTF.TBEIF bit = 0, otherwise
transmit data cannot be guaranteed.
I2C Ch.
n
Receive Data Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
I2CnRXD
15–8 –
0x00
–
R
–
7–0 RXD[7:0]
0x00
H0
R
Bits 15–8 Reserved
Bits 7–0
RXD[7:0]
The receive data buffer can be read through these bits.
I2C Ch.
n
Status and Interrupt Flag Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
I2CnINTF
15–13 –
0x0
–
R
–
12 SDALOW
0
H0
R
11 SCLLOW
0
H0
R
10 BSY
0
H0/S0
R
9
TR
0
H0
R
8
–
0
–
R
7
BYTEENDIF
0
H0/S0
R/W Cleared by writing 1.
6
GCIF
0
H0/S0
R/W
5
NACKIF
0
H0/S0
R/W
4
STOPIF
0
H0/S0
R/W
3
STARTIF
0
H0/S0
R/W
2
ERRIF
0
H0/S0
R/W
1
RBFIF
0
H0/S0
R
Cleared by reading the I2CnRXD reg-
ister.
0
TBEIF
0
H0/S0
R
Cleared by writing to the I2CnTXD
register.
Bits 15–13 Reserved
Bit 12
SDALOW
This bit indicates that SDA is set to low level.
1 (R):
SDA = Low level
0 (R):
SDA = High level
Bit 11
SCLLOW
This bit indicates that SCL is set to low level.
1 (R):
SCL = Low level
0 (R):
SCL = High level