EPC635 datasheet(24/97 Pages) EPC

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5.4. I2C Slave

The I2C-bus interface allows accessing the RW registers and the programming of the EEPROM registers which store the configuration pa-

rameters. It is the only interface through which the configuration registers can be accessed (Figure 68, Table 40 and Table 41) by the ap-

plication. It works as a slave device according to the I2C specification (refer to chapter 10.2.) with a transfer rate of up to 400 kbit/s in Fast

Mode (FM) or 1Mbit/s in Fast Mode plus (FM+). The I2C master such as an external CPU can set the transfer speed simply by driving the

SCL input at that frequency (up to 1MHz), therefore there is no prior register configuration or setting necessary.

I2C specification is supported in epc635 with following remarks/exceptions:

■ Only 7-bit addressing is supported.

■ Clock stretching is supported.

■ General call address: By transmitting 0x00 followed by 0x06 (issues software reset) or transmitting 0x00 followed by 0x04 (device ad-

dress reload), the programmable part (A0, A1) of the I2C address pins is overwritten by the initially scanned value through strap pins dur-

ing start-up or reset phase.

■ Software reset is supported.

■ Other uses of I2C bus are not supported.

5.4.1. Device addressing

The epc635 7-bit I2C device address is hard-wired to the value shown below in Figure 18. Two address bits A0, A1 can be optionally initial-

ized as 1 through strap pins (chapter 5.3.3.). In a typical single-camera 3D TOF imager application in which epc635 is directly connected

as a single I2C slave to a single I2C master, the strap pins can be used without any external pull-up resistors. In this case, the device ad-

dress is set after reset default as 0100000. In a multi-camera application with up to 4 epc635 devices connected on the same I 2C bus as

slaves or together with other I2C slaves talking to a single I2C master, external pull-up resistors can be utilized on the strap pins to initialize

different I2C device addresses in order to correctly identify different epc635 slaves on the bus.

Figure 18: Device address through I2C

5.4.2. I2C bus protocol notation

The following notation is used:

■ S

START condition

■ P

STOP condition

■ A

Acknowledge last byte (ACK)

■ A

Not-Acknowledge last byte (NACK)

■ Shaded part of protocol: transmitted by master

■ Unshaded part of protocol: transmitted by slave

Characteristics subject to change without notice

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