42.6.1 I/O Lines

Both TWD and TWCK are bidirectional lines, connected to a positive supply voltage via a current source or pullup resistor. 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 TWIHS, the user must program the PIO Controller to dedicate TWD and TWCK as peripheral lines. When High-speed Client mode is enabled, the analog pad filter must be enabled.

The user must not program TWD and TWCK as open-drain. This is already done by the hardware.