AT91SAM9260-CU ATMEL [ATMEL Corporation], AT91SAM9260-CU Datasheet - Page 15

• Manufacturer Part Number: AT91SAM9260-CU
• Description: AT91 ARM Thumb Microcontrollers
• Manufacturer: ATMEL [ATMEL Corporation]

5.3
6. I/O Line Considerations
6.1
6.2
6.3
6221IS–ATARM–12-Aug-08
Programmable I/O Lines Power Supplies
JTAG Port Pins
Test Pin
Reset Pins
The power supplies pins VDDIOM accept two voltage ranges. This allows the device to reach its
maximum speed either out of 1.8V or 3.3V external memories.
The target maximum speed is 100 MHz on the pin SDCK (SDRAM Clock) loaded with 30 pF for
power supply at 1.8V and 50 pF for power supply at 3.3V. The other signals (control, address
and data signals) do not exceed 50 MHz.
The voltage ranges are determined by programming registers in the Chip Configuration registers
located in the Matrix User Interface.
At reset, the selected voltage defaults to 3.3V nominal, and power supply pins can accept either
1.8V or 3.3V. Obviously, the device cannot reach its maximum speed if the voltage supplied to
the pins is 1.8V only. The user must program the EBI voltage range before getting the device out
of its Slow Clock Mode.
TMS, TDI and TCK are Schmitt trigger inputs and have no pull-up resistors.
TDO and RTCK are outputs, driven at up to VDDIOP0, and have no pull-up resistors.
The JTAGSEL pin is used to select the JTAG boundary scan when asserted at a high level (tied
to VDDBU). It integrates a permanent pull-down resistor of about 15 kΩ to GNDBU, so that it
can be left unconnected for normal operations.
The NTRST signal is described in
All the JTAG signals are supplied with VDDIOP0.
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 a bidirectional with an open-drain output integrating a non-programmable pull-up resis-
tor. It can be driven with voltage at up to VDDIOP0.
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 to VDDIOP0. Its value
can be found in the table “DC Characteristics” in the section “AT91SAM9260 Electrical Charac-
teristics” in the product datasheet.
The NRST signal is inserted in the Boundary Scan.
Section
6.3.
AT91SAM9260
15