Created it, 06/10/19
Update it, 06/10/25
N° Visitors
5. - SECOND EXPERIMENT : “EXAMINATION OF A ROCKER D IN THE MASTER-SLAVE CONFIGURATION”
With this handling, you will check the operation of a rocker D in the master-slave configuration. In a preceding experiment, you already had the occasion to examine the integrated circuit MM 74C74 containing two rockers D ; you will learn with better knowing the operation of this circuit by joining together some of the acquired points of the preceding experiments.
5. 1. - REALIZATION OF THE CIRCUIT
a) Disconnect the food and remove matrix the integrated circuit, remove group of connectors all the connections relating to the last experiment.
b) Introduce on the matrix two integrated circuits MM 74C00 (containing four circuits NAND each one) and an integrated circuit MM 74C04 (containing six reversers) into the positions indicated on the figure 16-a.
c) Carry out the connections described by the figure 16-a by using like habit the pieces of canned wire insulated recovered during the preceding experiments or cut to the good length in the strand which you have in your possession.
d) Put switch SW0 on position 0.
The electric diagram of the circuit that you have just carried out is represented by the figure 16-b. As you can observe it, the circuit is composed of two rockers R.S.C of the type which you already examined in practice preceding, connected one following the other.
The signal 
provided by the P0 button is applied
directly to the entry of the second rocker and through a reverser to the entry
of the first.
A second reverser, connected to the entry R of the first rocker, makes it possible to reverse the logical levels applied to the entries S and R by means of switch SW0.
Note that the first rocker is called Maître while second Esclave is called. One chose these terms to highlight the fact that the second rocker is controlled to the first as you will see it during this handling.
5. 2. - OPERATIONAL TEST
a) Connect the food. You observe that the LED L0 connected to the exit of the rocker MASTER is extinct, indicating that this exit is with the state L.
The LED L1 connected to the exit of the rocker SLAVE either is lit, or extinct, depending on the state of the circuit to the powering. This is not foreseeable and depends on the physical characteristics of the integrated circuit.
b) Commutate switch SW0 several times of continuation. You note that the exit of the rocker MASTER follows the state of the entry, going to the state H (L0 lit) or to the state L (L0 extinct) when switch SW0 is commutated respectively on position 1 (entry of the circuit to the state H) or on position 0 (entry of the circuit to the state L).
On the other hand, the LED L1 does not announce any change of state at exit of the rocker SLAVE.
With this test, you ensured yourselves that the rocker MASTER is sensitive to the level of the input signal when the entry C of the circuit is with the state L, while the rocker SLAVE is insensitive there.
c) Put now switch SW0 on position 1 so as to light L0.
d) Press on the P0 button and maintain it in this position thus applying to the entry of order C of the circuit a level H.
You observe that L1 ignites or remains lit if it were it already ; this indicates that the state at exit of the MASTER was transferred to the exit from the SLAVE.
e) Keeping P0 always inserted, commutate several times switch SW0.
You observe that L0 remains lit, sign which the MASTER does not change state and which it is thus insensitive with the variations of the level of the entry. In the same way, by observing L1, you note that the SLAVE, also, does not change a state.
f) Slacken the P0 button and commutate switches SW0 on several occasions.
This time, you note that L0 ignites and dies out each time you act on SW0. That indicates that the exit of the MASTER again follows the changes of level of the entry. On the other hand, L1 constantly remains lit indicating that the exit of the SLAVE does not change a state.
g) Put switch SW0 on position 0 so that L0 dies out.
h) Support and maintain P0 in this position ; L1 dies out.
i) Slacken the P0 button : L1 remains extinct.
With this test, you checked by the practice the operation of the MASTER-SLAVE circuit which can be summarized as follows :
when the entry of order C is with the state L,
the MASTER reproduces at exit the logical
state present on the entry. The SLAVE is on
the other hand isolated from the MASTER and
it is thus insensitive to any variation of state appearing on the entry.
When the entry of order C places to the
state H, the MASTER
is isolated from the entry and its exit becomes independent of the state of the
entry, and the state present at the exit of the MASTER
is transferred to the exit from the SLAVE.
We can thus conclude that in a rocker of the MASTER-SLAVE type the transfer of the logical states of the terminals of entry to the output is done in two times : time to carry out this transfer is equal to the duration of a clock pulse (which can be about 1 µs or even less in the circuits usually employed).
When the clock pulse (entered C) master key of H with L, the data present at the entry is transferred to the MASTER (and there is no change at the exit of the rocker, i.e. of the SLAVE).
At the time of the transition from L to H of the clock pulse, the data present at the exit of the MASTER is transferred to the SLAVE, therefore at the exit of the rocker.
6. - THIRD EXPERIMENT : EXAMINATION
OF A ROCKER J.K.
Rocker J.K. Master-slave, as you will see it during this handling, is the type of most flexible rocker of the employment among all those which you will have to examine.
For this handling, you will use the integrated circuit CD 4027 (or type are equivalent) containing two rockers J.K. MASTER SLAVE whose entries and exits are connected to the pins according to the diagram of figure 17.
The two rockers are identical and as you can notice it, each one of these rockers has five entries.
two principal entries J and K
an entry of clock CLOCK
two auxiliary entries SET and RESET
The functions of these entries will be checked directly by the handling which will follow.
The exits of each rocker are two, Q
and 
,
and they are complementary one of the other.
6. 1. - REALIZATION OF THE CIRCUIT
a) Disconnect the food and remove matrix and group of connectors all the integrated circuits and the connections relating to the preceding experiment.
b) Introduce the circuit CD 4027 on the matrix into the position indicated by the figure 18-a, and carry out the connections deferred in this same figure.
The electric diagram of the circuit carried out is represented by the figure 18-b. As you can observe it, the entries J2 and K2 are connected respectively to SW0 and SW1, while the entries SET 2 and RESET 2 are connected to SW2 and SW3.
The Q2
exits and 2
are connected to the LED L0 and L1.
Since, as we already said, the two rockers constituting the integrated circuit are perfectly identical, the operational test is limited to only one of them, therefore all the pins of 9th with 15th are left free.
6. 2. - CONTROL OF OPERATION
a) Feed the circuit: one of the two LED L0 and L1 ignites. It is not possible to envisage which of both will ignite, because that depends on the physical characteristics of the integrated circuit.
b) Commutate switch SW2 on position 1 thus putting the entry SET 2 at the state H. the LED L0, connected to the Q2 exit ignites or remains lit.
c) Give switch SW2 on position 0 and commutate switch SW3 on position 1, applying this manner the state H to the entry RESET 2.
You observe that the LED
L0 dies out, while the LED L1
connected to exit 2
ignites.
d) Commutate several times
switches SW2 and SW3
by taking care however never to put them both on position 1.
You notice that each time switch SW2 is in
position 1 (SET 2
on the level H), the Q2
exit also passes on the level H, while2
goes on the level L.
On the contrary, when SW3
is in position 1 (RESET
2 on the level H), the Q2
exit passes on the level L and 2
on the level H.
e) Put SW2 on position 1 (SET 2 with the state H) and SW3 on position 0 (RESET 2 with the state L) so that L0 ignites, then actuate as many time as you want switches SW0 (entered J2), SW1 (entered K2) as well as the P0 button (entered CLOCK 2).
You note that the state from the Q2
exits and 2
does not vary, which indicates that the changes of state of the entries J,
K and CLOCK do not determine any
swing of the state of the exits.
f) After having commutated SW2 on position 0 (SET 2 with the state L) and SW3 on position 1 (RESET 2 in a state H) so that L1 ignites, remade the preceding test by actuating several times SW0, SW1 and P0.
You observe that in this case also, the entries J, K and CLOCK do not cause change of the state of the exits.
With these tests, you could note that the entries SET and RESET force the rocker in one of its two possible states, independently of the other entries.
g) Put two switches SW2 and SW3 on position 1. In this case, the LED L0 and L1 ignite both ; however this condition is generally neither useful, nor advisable.
h) Commutate simultaneously SW2 and SW3 on position 0. The rocker will go to a state which will depend on that of the two entries SET and RESET which remained in the last on position 1.
i) Put the rocker at state 0 so that L0 is extinct and L1 lit. Mettez SW3 one moment on position 1 then again replace it on position 0.
j) Leaving SW2 and SW3 on position 0, commutate also SW0 and SW1 on position 0, you thus apply the state L to the two entries J2 and K2. Support and slacken then the P0 button. You observe that the rocker remains with state 0 (extinct LED L0).
k) Put SW0 on position 1 (J2 with the state H), leave SW1 on position 0 (K2 with the state L) and press on the P0 button. You observe that L0 ignites, while L1 dies out.
l) Slacken P0 : L0 remains lit.
m) Put SW0 on position 0 (J2 with the state L) and SW1 on position 1 (K2 with the state H). Insert then slacken the P0 button. You note that L0 dies out while L1 ignites.
n) Now commutate SW0 on position 1 ; in this manner J2 and K2 are on the level H.
o) Support known P0 : L0 ignites and L1 dies out.
p) Slacken then support again on P0 : L0 dies out and L1 ignites.
Continuously to insert and slacken P0, you note each time a change of state at exit. One can thus conclude that when the entries J and K are both on the level H, the rocker changes state each time a positive impulse arises on entry CLOCK, i.e. each time there is a transition from the level L to the level H.
The results of the tests carried out are indicated in figure 19 where the table of operation of the rocker in question is deferred.
You point out that in this table, symbol X means “indifferent state” while the arrow with the point directed to the top represents a transition from the clock signal of the level L towards the level H. the letters S and R indicate respectively the entries SET and RESET.
In conclusion, the operation of ROCKER J.K. MASTER-SLAVE can summarize itself as follows :
the two entries SET and RESET
must be on the level L to obtain the normal
operation of the rocker with the clock signal.
if the entry J and the entry K
are both with the state L, there is not any
change of state at the exit when a positive transition arises on entry CLOCK.
if the entry J is at the state H
and the entry K with the state L,
the rocker passes (or remains if it is there already) to state 1
(exit Q on the level H
and exit
on the level L) when a positive transition
is applied to entry CLOCK.
if the entry J is at the state L
and the entry K with the state H,
the rocker passes (or remains if it is there already) to state 0
(exit Q on the level L
and exit
on the level H) when a positive transition
is applied to entry CLOCK.
if the entry J and the entry K
are both with the state H, the rocker
changes state each time a positive transition from level is applied to entry CLOCK.
In this case, one says that the rocker functions in mode T
(toggle). This operating mode is at the base
of much type of electronic systems of counting as you will see it thereafter.
if the entry SET is at the level H
and the entry RESET on the level L,
the rocker passes immediately to state 1 (Q
on the level H and
the level L) without a positive impulse of
clock being necessary.
if the entry RESET is at the level H
and the entry SET on the level L,
the rocker passes immediately to state 0 (Q
on the level L and
the level H) without a positive impulse of
clock being necessary.
if the entries SET and RESET
are both on the level H, the two exits Q
and
pass immediately to state 1. This
condition must however be avoided.
for a normal operation of the rocker, the clock signal must free from parasites
and be characterized by a time of transition from the level L
to the level H lower than 5
µs, such as for example that obtained while acting on the button P0
(contact P0
on the group of connectors).
Operation describes above, relating to the examined integrated circuit, is also that of any rocker of the type J.K.
However, it may be that the entries SET and RESET instead of being active on the level H are it on the level L. That means that these two entries must be maintained on the level H for an operation of the rocker with the clock signal.
On the other hand, when one wants to position the rocker independently of the clock signal, the entry SET or the entry RESET must be carried on the level L.
In this case, a small circle (sign of inversion) is placed on the two entries SET and RESET in the diagram representing the rocker.
There are also rockers requiring a negative transition from clock, i.e. a signal going from the level H on the level L.
In this case also, a small circle is deferred on the terminal of entry CLOCK in the diagram; it indicates that entry CLOCK is active with a negative transition from the clock signal.
Rocker J.K is certainly more flexible of employment than the rocker D and present compared to the latter some characteristics which make it irreplaceable in certain applications. In the other cases, the rocker D is often preferred bus having only one entry D, its employment reduces the complexity of the systems. Moreover, this rocker D has the advantage of being a little more economic and of consuming less energy than rocker J.K.
Click
here for the following lesson or in the synopsis envisaged to this end. |
High
of page |
 Preceding
page |
Following
page |
