Product Specs

Table Of Contents
49 TWI I
2
C compatible two-wire interface
Page
522
VDD VDD
R
R
TWI slave
Address = b1011011
SCL SDA
TWI slave
(Sensor)
Address = b1011000
SCL SDA
TWI slave
(EEPROM)
Address = b1011001
SCL SDA
SCL
SDA
TWI master
49 TWI I
2
C compatible two-wire interface
The TWI master is compatible with I
2
C operating at 100 kHz and 400 kHz.
PSELSDA
PSELSCL
PSELSDA
STARTRX
STARTTX
SUSPEND
RESUME
STOP
Figure 154: TWI master's main features
RXDRDY
TXDSENT
BB
SUSPENDED
ERROR
STOPPED
49.1 Functional description
This TWI master is not compatible with CBUS. The TWI transmitter and receiver are single buffered.
See, Figure 154: TWI master's main features on page 522.
A TWI setup comprising one master and three slaves is illustrated in Figure 155: A typical TWI setup
comprising one master and three slaves on page 522. This TWI master is only able to operate as the only
master on the TWI bus.
Figure 155: A typical TWI setup comprising one master and three slaves
This TWI master supports clock stretching performed by the slaves. The TWI master is started by triggering
the STARTTX or STARTRX tasks, and stopped by triggering the STOP task.
If a NACK is clocked in from the slave, the TWI master will generate an ERROR event.
49.2 Master mode pin configuration
The different signals SCL and SDA associated with the TWI master are mapped to physical pins according to
the configuration specified in the PSELSCL and PSELSDA registers respectively.
If a value of 0xFFFFFFFF is specified in any of these registers, the associated TWI master signal is not
connected to any physical pin. The PSELSCL and PSELSDA registers and their configurations are only used
RXD TXD
RXD TXD
(signal) (signal)