Instruction manual

BD416 • 6
are always in opposite states. Our flip-flops also have set and reset controls.
When the set control is pulsed low and returned to a high level the “Q” output
is set to a high level. If reset is pulsed low and returned high the “Q” output is
set to a low level. We’ll talk more about these signals later.
The same inputs, B0 thru B3, are connected to the “D inputs, pins 2 and 12 of
U1 and U5, of the 4 “D” flip-flops. The clock, or trigger, inputs of these flip-
flops, pins 3 and 11 on U1 and U5, are connected to U2 pin 3. U3 is called an
“exclusive or” gate which has 2 inputs. An “OR gate” simply sets it’s output to
a high level if either or both of it’s inputs is high. Since this is a special type of
“OR” gate called an “exclusive OR” it will only set it’s output high when only
one of it’s inputs is high. If both inputs are high it’s output will be set low. This
is very useful because if one of it’s inputs is locked to a high it will set it’s
output to the opposite state of the other input. What’s so great about that you
ask? Well read on and you’ll see what we use it for.
Notice that U2 pin 2 is connected to the “VALID DATA” input and pin 1 is
connected to a high level by R1. Also notice that pin 1 is connected to jumper
H1. By placing a jumper on H2, U2 pin 3 will follow the “VALID DATA” input.
If the jumper is removed pin 3 will be the opposite level of the “VALID DATA”
input. In this way the BD416 can be configured to latch the input data into the
“D” flip-flops on either a low or high level “VALID DATA” signal. By setting up
the data on the input lines B0 – B3 and then triggering that data into the flip-
flops using the “VALID DATA” input the 16 output lines will be set and latched
to the data value placed on the inputs. It will remain in that state until another
“VALID DATA” signal latches in another input value.
The last operation we need to look at is the “SET” and “RESET” operation of
the flip-flops. “INIZALIZE” jumper H3 is used to determine how the outputs
are set up when power is applied in the latched configuration. When power is
first applied to the BD416 capacitor C6 is discharged and this is a low logic
level and can be applied to either the set, pins 1 and 13, or reset, pins 4 and
10, of U1 and U5 by the placement of the “INITIALIZE” jumper H3. A short
time after power is applied, C6 will rise to a high level and allow the flip-flops
to operate as described above. If “SET” is selected the “Q” outputs of U1 and
U5 will all be set to 0 and output “O” will be set to a low state. If “RESET” is
selected the “Q” outputs of U1 and U5 will all be set to 1 and output “15” will
be set to a low state.
The BD416 requires a power supply level of 5VDC to operate. This power is
applied to either J3 or J6 terminal blocks. If you are using multiple Ramsey
interface modules or other products requiring 5VDC power you may feed the
power thru the DB4-16 module using J3 and J6.