Digital I/O Specifications

Specifications are Typical unless otherwise noted.

Number of DIO channels

40

Direction control

Individually programmable as input or output

Logic level

5 V compatible LVTTL input; 3.3 V LVTTL output

Pull-up/down

40.2 kΩ pull-up to 3.3 V[1]

Protection

±30 V

Input logic levels
Input low voltage, VIL

Minimum

0 V

Maximum

0.8 V

Input high voltage, VIH

Minimum

2.0 V

Maximum

5.25 V

Output logic levels
Output low voltage, VOL sinking 4 mA

Minimum

0 V

Maximum

0.4 V

Output high voltage, VOH sourcing 4 mA

Minimum

2.4 V

Maximum

3.465 V

Minimum output pulse width

20 ns

Maximum frequencies for secondary digital functions

SPI

4 MHz

PWM

100 kHz

Quadrature encoder input

100 kHz

I2C

400 kHz [2]

UART lines

Maximum baud rate

230,400 bps

Data bits

5, 6, 7, 8

Stop bits

1, 2

Parity

Odd, Even, Mark, Space

Flow control

XON/XOFF

1 The NI ELVIS III enables a 40.2 kΩ pull-up to 3.3 V on the DIO lines by default. If the NI ELVIS III detects an application board designed for the NI ELVIS II/II+, it enables a 40.2 kΩ pull-down to Ground on the DIO lines instead.

2 I2C requires an additional pull-up resistor on I2C_SCL and I2C_SDA for correct operation. Some I2C devices already include suitable pull-up resistors, others require that the resistors be added explicitly on the application board. Typical resistor values range from 1 kΩ to 10 kΩ.