ATAM894X-TNQY ATMEL [ATMEL Corporation], ATAM894X-TNQY Datasheet - Page 25

• Manufacturer Part Number: ATAM894X-TNQY
• Description: 8k-flash Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

6.2.2
4679D–4BMCU–05/05
Bi-directional Port 2
Figure 6-2.
As all other bi-directional ports, this port includes a bit-wise-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.
However, Port 2 has an increased drive capability and an additional low resistance pull-up/-
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
pin must not be pulled down (active or passive) to V
resenting a resistor of less than 150 k . This prevents the circuit from unintended switching to
test mode enable through the application circuitry at pin BP20/NTE. Resistors less than 150 k
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.
Master reset
OUT
IN
I/O Bus
Bi-directional Port 1
(Direction)
(Data out)
D
P1DATy
S
R
Reset
R
NQ
Q
Q
DD
by an additional internal strong pull-up transistor. This
(1)
Flash options
SS
during reset by any external circuitry rep-
(1)
(1)
Switched
pull-up
V
DD
Switched
(1)
pull-down
(1)
V
DD
ATAM894
Static
pull-up
BP1y
Static
pull-down
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