Datasheet

708
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
39.6 Product Dependencies
39.6.1 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 39-2). 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 perform the following
step:
 Program the PIO controller to dedicate TWD and TWCK as peripheral lines.
The user must not program TWD and TWCK as open-drain. It is already done by the hardware.
39.6.2 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.
39.6.3 Interrupt
The TWI interface has an interrupt line connected to the Interrupt Controller. In order to handle interrupts, the Interrupt
Controller must be programmed before configuring the TWI.
Table 39-4. I/O Lines
Instance Signal I/O Line Peripheral
TWI0 TWCK0 PA31 A
TWI0 TWD0 PA30 A
TWI1 TWCK1 PC1 C
TWI1 TWD1 PC0 C
Table 39-5. Peripheral IDs
Instance ID
TWI0 9
TWI1 10