19 UNIVERSAL SERIAL INTERFACE WITH LCD INTERFACE (USIL)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
19-15
0x6
0x6
0x2
0x1
Transfer data n
D7
D6
D5
D4
D3
D2
D1
D0
ACK
ACK
USIL_CK pin (output)
USIL_CK pin (input)
USIL_DI pin (output)
USIL_DI pin (input)
IMTGMOD[2:0]
IMTG (write)
IMBSY
IMSTA[2:0]
TD[7:0]
IMIF
Stop interrupt
End of transmission
interrupt
Receive
ACK interrupt
Receive
ACK interrupt
*
*
*
*
*
0x2
0x1
0x5
0x5
(2) Data transmission
→
Stop condition
*
When IMIF is cleared via software, IMSTA[2:0] is also cleared to 0x0.
5.3.2 I
Figure 19.
2
C Master Data Transmission Timing Chart
(1) Generating start condition
I
2
C data transfer starts when the I
2
C master device generates a start condition. The start condition applies
when the SCL line is maintained at high and the SDA line is pulled down to low.
To generate a start condition in this I
2
C master, set IMTGMOD[2:0] to 0x0 (default) and write 1 to IMTG.
SDA (USIL_DI)
SCL (USIL_CK)
Start condition
5.3.3 Start Condition
Figure 19.
IMBSY is set to 1 while a start condition is being generated. When the start condition is generated, IMBSY
is reset to 0 and IMSTA[2:0] is set to 0x0. The I
2
C bus is busy from this point on.
Note: Other operations cannot be started before a start condition is generated.
(2) Sending slave address and transfer direction bit
After a start condition has been generated, send the address of the slave device to be communicated and a
transfer direction bit. I
2
C slave addresses are either 7-bit or 10-bit. This module uses an 8-bit transfer data
buffer to send the slave address and transfer direction bit, enabling single transfers in 7-bit address mode. In
10-bit mode, data is sent twice or three times under software control. Figure 19.5.3.4 shows the configura-
tion of the address data.
Slave address
7-bit address
Transfer direction
0: master
→
slave (transmission)
1: slave
→
master (reception)
A6
A5
D7
D6
A4
D5
A3
D4
A2
D3
A1
D2
A0
D1
R/W
D0
8 low order slave address bits
A7
A6
D7
D6
A5
D5
A4
D4
A3
D3
A2
D2
A1
D1
A0
D0
2 high order
slave address bits
10-bit address
1
First transmit data
Second transmit data
Third transmit data
1
D7
D6
1
D5
1
D4
0
D3
A9
D2
A8
D1
0
D0
1
1
D7
D6
1
D5
1
D4
0
D3
A9
D2
A8
D1
1
D0
When the I
2
C master performs data reception, issue a repeated start condition after the second data
has been sent and then send the third data as shown below.
2 high order
slave address bits
5.3.4 Transmit Data Specifying Slave Address and Transfer Direction
Figure 19.