XIO2001 datasheet(35/128 Pages) TI

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GPIO4 // SCL

GPIO3 // SDA

VDD_33

SCL

SDA

XIO2001

Serial

EEPROM

XIO2001

www.ti.com

SCPS212D – MAY 2009 – REVISED JANUARY 2010

edge of PERST or GRST, whichever occurs later in time, the SCL terminal is checked for a pullup resistor.

If one is detected, then bit 3 (SBDETECT) in the serial-bus control and status register (see Section 4.58)

is set. Software may disable the serial-bus interface at any time by writing a 0b to the SBDETECT bit. If

no external EEPROM is required, then the serial-bus interface is permanently disabled by attaching a

pulldown resistor to the SCL signal.

The bridge implements a two-terminal serial interface with one clock signal (SCL) and one data signal

(SDA). The SCL signal is a unidirectional output from the bridge and the SDA signal is bidirectional. Both

are open-drain signals and require pullup resistors. The bridge is a bus master device and drives SCL at

approximately 60 kHz during data transfers and places SCL in a high-impedance state (0 frequency)

during bus idle states. The serial EEPROM is a bus slave device and must acknowledge a slave address

equal to A0h. Figure 3-13 illustrates an example application implementing the two-wire serial bus.

Figure 3-13. Serial EEPROM Application

3.10.2 Serial-Bus Interface Protocol

All data transfers are initiated by the serial-bus master. The beginning of a data transfer is indicated by a

start condition, which is signaled when the SDA line transitions to the low state while SCL is in the high

state, as illustrated in Figure 3-14. The end of a requested data transfer is indicated by a stop condition,

which is signaled by a low-to-high transition of SDA while SCL is in the high state, as shown in

Figure 3-14. Data on SDA must remain stable during the high state of the SCL signal, as changes on the

SDA signal during the high state of SCL are interpreted as control signals, that is, a start or stop condition.

Figure 3-14. Serial-Bus Start/Stop Conditions and Bit Transfers

Feature/Protocol Descriptions

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