ATAM862 datasheet(36/110 Pages) ATMEL

36 / 110 page

4554E–4BMCU–05/06

ATAM862-3

Figure 22-1. Bi-directional Port 1

22.2

Bi-directional Port 2

As all other bi-directional ports, this port includes a bitwise programmable Control Register

(P2CR), which enables the individual programming of each port bit as input or output. It also

opens up the possibility of reading the pin condition when in output mode. This is a useful fea-

ture for self testing and for serial bus applications.

Port 2, however, has an increased drive capability and an additional low resistance

pull-up/pull-down transistor mask option.

Care should be taken connecting external components to BP20/NTE. During any reset phase,

the BP20/NTE input is driven towards V

DD by an additional internal strong pull-up transistor. This

pin must not be pulled down (active or passive) to V

SS during reset by any external circuitry rep-

resenting a resistor of less than 150 k

Ω. This prevents the circuit from unintended switching to

test mode enable through the application circuitry at pin BP20/NTE. Resistors less than 150 k

Ω

might lead to an undefined state of the internal test logic thus disabling the application firmware.

To avoid any conflict with the optional internal pull-down transistors, BP20 handles the pull-down

options in a different way than all other ports. BP20 is the only port that switches off the

pull-down transistors during reset.

OUT

Reset

I/O Bus

Master reset

P1DATy

(Data out)

(Direction)

BP1y

V DD

Switched

pull-up

*) Configurable

V DD

Static

pull-up

Static

pull-down

Switched

pull-down

ATAM862 Datasheet(PDF) 36 Page - ATMEL Corporation

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