Instruction manual

BD416 • 5

TABLE 1: BD416 INPUT/OUTPUT

OK, now it gets a little more interesting. We’re going to look at the latched

configuration operation. Everything starts off just like the non-latched

configuration except now U4 is set up to select the other 4 inputs on pins 2, 5,

11 and 14 by placing a jumper on the “LATCH” configuration jumper block.

These inputs are connected to the “Q” outputs of 4 circuits called “D” flip-flops,

2 each in U1 and U5. Yea, I know what you may want to know now, what the

heck is a “D” flip-flop? Well here’s a hopefully easy to understand explanation.

A “flip-flop” is, as it’s name suggests, a device, in this case a logic circuit, that

has one of two output states that can be can be “flipped” between either a high

or low by a logic signal. In other words it can be “flipped” back and forth

between the two states or “flip-flopped”. In the case of our application the flip-

flops are a special type where the output is set to the same state as an input

which is called the “D” input. A trigger signal, called a clock, determines when

the output assumes the state of the “D” input. The flip-flops used in the BD416

actually have 2 outputs called “Q” and “Qnot”, (“Qnot” is indicated by a Q with

a line over it in the schematic), and we only use the “Q” output. These outputs

INPUT OUTPUT

0 1 2 3 4 5 6 7 8 9 1

0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 1 0 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1

0 1 0 0 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1

0 1 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1

0 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1

0 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1

1 0 0 0 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1

1 0 0 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1

1 0 1 0 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1

1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1

1 1 0 0 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1

1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1

1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0