at91cap7e ATMEL Corporation, at91cap7e Datasheet - Page 15

• Manufacturer Part Number: at91cap7e
• Description: Customizable Microcontroller
• Manufacturer: ATMEL Corporation

6. I/O Line Considerations
6.1
6.2
6.3
6.4
6.5
8549A–CAP–10/08
JTAG Port Pins
Test Pin
Reset Pins
PIO Controllers
Shut Down Logic pins
TMS, TDI and TCK are Schmitt trigger inputs and have no pull-up resistors.
TDO and RTCK are outputs, driven at up to VDDIO, and have no pull-up resistor.
The JTAGSEL pin is used to select the JTAG boundary scan when asserted at a high level. It
integrates a permanent pull-down resistor of about 15 kΩ to GNDBU, so that it can be left uncon-
nected for normal operations.
The NTRST signal is described in the Reset Pins paragraph. All the JTAG signals are supplied
with VDDIO.
The TST pin is used for manufacturing test purposes when asserted high. It integrates a perma-
nent pull-down resistor of about 15 kΩ to GNDBU, so that it can be left unconnected for normal
operations. Driving this line at a high level leads to unpredictable results.
This pin is supplied with VDDBU.
NRST is an open-drain output integrating a non-programmable pull-up resistor. It can be driven
with voltage at up to VDDIO.
NTRST is an input which allows reset of the JTAG Test Access port. It has no action on the
processor.
As the product integrates power-on reset cells, which manages the processor and the JTAG
reset, the NRST and NTRST pins can be left unconnected.
The NRST and NTRST pins both integrate a permanent pull-up resistor of 100 kΩ minimum to
VDDIO.
The NRST signal is inserted in the Boundary Scan.
All the I/O lines which are managed by a PIO Controller integrate a programmable pull-up resis-
tor of 100 kΩ minimum. Programming of this pull-up resistor is performed independently for each
I/O line through the PIO Controllers.
After reset, all the I/O lines default as inputs with pull-up resistors enabled, except those which
are multiplexed with the External Bus Interface signals that must be enabled as Peripheral at
reset. This is explicitly indicated in the column “Reset State” of the PIO Controller multiplexing
tables.
The SHDN pin is an output only, which is driven by the Shut Down Controller only at low level. It
can be tied high with an external pull-up resistor at VDDBU only.
AT91CAP7E
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