16 I
2
C (I2C)
16-2
Seiko Epson Corporation
S1C31D50/D51 TECHNICAL MANUAL
(Rev. 2.00)
16.2 Input/Output Pins and External Connections
16.2.1 List of Input/Output Pins
Table 16.2.1.1 lists the I2C pins.
Table 16.2.1.1 List of I2C Pins
Pin name
I/O
*
Initial status
*
Function
SDAn
I/O
I
I
2
C bus serial data input/output pin
SCLn
I/O
I
I
2
C bus clock input/output pin
*
Indicates the status when the pin is configured for the I2C.
If the port is shared with the I2C pin and other functions, the I2C input/output function must be assigned to the port
before activating the I2C. For more information, refer to the “I/O Ports” chapter.
16.2.2 External Connections
Figure 16.2.2.1 shows a connection diagram between the I2C in this IC and external I
2
C devices.
The serial data (SDA) and serial clock (SCL) lines must be pulled up with an external resistor.
When the I2C is set into master mode, one or more slave devices that have a unique address may be connected to the
I
2
C bus. When the I2C is set into slave mode, one or more master and slave devices that have a unique address may be
connected to the I
2
C bus.
SCLn
V
DD
SDAn
S1C31
Serial data (SDA)
Serial clock (SCL)
I
2
C bus
External
I
2
C device
External
I
2
C device
Figure 16.2.2.1 Connections between I2C and External I
2
C Devices
Notes: • The SDA and SCL lines must be pulled up to a V
DD
of this IC or lower voltage. However, if the
I2C input/output ports are configured with the over voltage tolerant fail-safe type I/O, these
lines can be pulled up to a voltage exceeding the V
DD
of this IC but within the recommended
operating voltage range of this IC.
• The internal pull-up resistors for the I/O ports cannot be used for pulling up SDA and SCL.
• When the I2C is set into master mode, no other master device can be connected to the I
2
C
bus.