16.5 Auxiliary Digital I/O on J3

J3 contains 3 digital outputs and 4 digital inputs that can be used for general purpose digital I/O or for A/D and counter/timer functions. The operation of these bits is controlled with various bits in two control registers.

Outputs

Ctr 2 Out / Dout 2 J3 pin 42

The function of this pin is determined by OUT2EN, Base + 10 bit 5:

1	Counter 2 output is routed to this pin
0	This pin is controlled by bit DOUT2 at Base + 1 bit 2

Dout 1 J3 pin 43

This pin is always the value written to DOUT1 at Base + 1 bit 1.

Ctr 0 Out / Dout 0 J3 pin 44

The function of this pin is determined by OUT0EN, Base + 10 bit 4:

1	Counter 0 output is routed to this pin
0	This pin is controlled by bit DOUT0 at Base + 1 bit 0

Inputs

Extclk / Din3 J3 pin 45

This signal may always be read at Base + 4 bit 3. It may function as an external clock to control A/D conversion timing when CLKEN = 1 and CLKSEL = 0 in Base + 9.

Extgate / Din2 J3 pin 46

This signal may always be read at Base + 4 bit 2. It may function as an external gate to enable and disable A/D conversions when GT12EN = 1 in Base + 10 bit 0.

Gate 0 / Din1 J3 pin 47

This signal may always be read at Base + 4 bit 1. It may function as an external gate for Counter 0 when GT0EN = 1 in Base + 10 bit 2. When used as a gate it is active high, meaning that Counter 0 will count as long as it is high and will not count when it is low.

Clk 0 / Din0 J3 pin 48

This signal may always be read at Base + 4 bit 0. It may function as an external clock for counter 0 when SRC0 = 0 in Base + 10 bit 1. When used as a clock for Counter 0, the rising edge is active.