Datasheet

SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
824
36.5 Application Block Diagram
Figure 36-2. Application Block Diagram
36.5.1 I/O Lines Description
36.6 Product Dependencies
36.6.1 I/O Lines
Both TWD and TWCK are bidirectional lines, connected to a positive supply voltage via a current source or pull-up
resistor (see Figure 36-2). When the bus is free, both lines are high. The output stages of devices connected to the
bus must have an open-drain or open-collector to perform the wired-AND function.
TWD and TWCK pins may be multiplexed with PIO lines. To enable the TWI, the programmer must program the
PIO controller to dedicate TWD and TWCK as peripheral lines.
The user must not program TWD and TWCK as open-drain. This is already done by the hardware.
36.6.2 Power Management
The TWI interface may be clocked through the Power Management Controller (PMC), thus the programmer must
first configure the PMC to enable the TWI clock.
Host with
TWI
Interface
TWD
TWCK
Atmel TWI
Serial EEPROM
I²C RTC
I²C LCD
Controller
Slave 1 Slave 2 Slave 3
V
DD
I²C Temp.
Sensor
Slave 4
Rp: Pull-up value as given by the I²C Standard
Rp Rp
Table 36-3. I/O Lines Description
Pin Name Pin Description Type
TWD Two-wire Serial Data Input/Output
TWCK Two-wire Serial Clock Input/Output
Table 36-4. I/O Lines
Instance Signal I/O Line Peripheral
TWI0 TWCK0 PA4 A
TWI0 TWD0 PA3 A
TWI1 TWCK1 PB5 A
TWI1 TWD1 PB4 A