Go Down

Topic: TPIC6B595 driving 8*8 Matrix (Read 1 time) previous topic - next topic

Wu-Mokun-Tian

Hello

I am the poster of MAX-7219 controlling Electromagnets

in that topic, I have got a advice which driving a matrix with 8 chips named TPIC6B595. So, I bought new chips and some new micro relays.


it's the single array's circuit diagram. for clearly knowing what happened in this board, I add 8 LED lights.



2 rows in 1 board. I made 4 boards in same way.



all of them

I wrote a program testing the board. but, the problem:

2 days ago, I have tested the single row with 1 tpic6b595 chip. it could work.

today, I connect 2 rows, rewrote a program:
Code: [Select]

int dataPin = 6; // SerIn = Data in,
int latchPin = 7; // REGISTER CLOCK = latchPin
int clockPin = 8; // SHIFT REGISTER CLOCK = clockPin

byte anim[2]= {
B00000000,
B11111111
};

void setup() {
  pinMode (dataPin, OUTPUT);
  pinMode (latchPin, OUTPUT);
  pinMode (clockPin,OUTPUT);

      digitalWrite(latchPin, LOW);
      delay(10);
      shiftOut(dataPin, clockPin, LSBFIRST, anim[2]); // digitOne
      delay(10);
      digitalWrite(latchPin, HIGH);
      delay(1000);
      return;
}

void loop() {
}


whatever I modify the byte anim[2] code. the LED lights always be random, not under control.


Wawa

And the red LEDs are connected to....
And the micro relays are...

Where are the decoupling caps.
You can't use digital chips without decoupling caps.
At least one 100n cap per chip, very close to the chip's VCC and ground.
Leo..

Wu-Mokun-Tian

And the red LEDs are connected to....
And the micro relays are...

Where are the decoupling caps.
You can't use digital chips without decoupling caps.
At least one 100n cap per chip, very close to the chip's VCC and ground.
Leo..


micro relay is the Panasonic NAIS produced AQY272. only 1.5v could driven it work.


I made reference to this method on picture. when I test only one chip, it works. so, I copy that way to build others

Grumpy_Mike

Shift out only outputs one byte, you need to use it twice if you have two shift registers.
You have no decoupling capacitors on the circuit. You seem to be ignoring this fact.

Wawa

Not sure what you're doing here. It seems you're driving small 24volt solenoids.
If they are 24volt/<=150mA, then those micro relays are not needed.
The TPIC6B595 was recommended because it has inbuils mosfets that can directly drive <=150mA solenoids.
The TPIC also has active voltage clamps, so no kickback diodes needed.
If you are using those micro relays, you have to add kickback diodes across the solenoids.
Failing to do so could damage those micro relays first time the solenoid turns off.
Leo..

Wu-Mokun-Tian

I got 2 things:

1, decoupling caps
2, kickback diodes

Is the caps connected with TPIC chip? so, I have to bring 8 caps back?

Between micro relay and electromagnet, I add a 220Ω resistor. Does this resistor worked same effect compared with kickback diodes

Wawa

I think you were told to use the 74HC595 with mosfets.

OR...

The TPIC6*595..... without anything else.

Now you have choosen for relays again.


So what is the current rating of those 24volt solenoids.

Post a link.
Leo..

Wawa

Between micro relay and electromagnet, I add a 220Ω resistor. Does this resistor worked same effect compared with kickback diodes
No.

Wu-Mokun-Tian

#8
Aug 27, 2016, 06:02 am Last Edit: Aug 27, 2016, 06:26 am by Wu-Mokun-Tian


40/25, the current rating is 0.34A.


what is the kickback diode? I'm not sure that kickback meaning commutation diode.

is this right? for avoid connect wrong electrode, we could series connect a kickback/ commutation diode to protect instrument.


but, My electromagnets are just a copper coil, no matter what electrode you connected, they always work that might with diff field direction.

==============go back to the decoupling caps============
I have already bought 10 decoupling caps (100 nF), which pin could I add this into chips? or series connect with every mosfets?



Wawa

A diode across the solenoid kills the voltage spike when the solenoid turns off.
A simple/cheap 1N4004 is fine for a 350mA solenoid.

Now we know the solenoid current, we can advise parts.

If you had bought the TPIC6A595 (the 350mA A version), you could have switched the solenoids directly with that chip. No other parts needed. Not even kickback diodes.
Only a 100n decoupling caps from VCC to ground.

If you already have the TPIC6B595 (150mA max), then you have to use extra parts (relays or mosfets).
And kickback diodes, to protect the relays or mosfets.

If you are going to use relays or mosfets, then a common/cheap 74HC595 (6mA) would have been enough.
But the TPIC6B595 is also ok.
Remember that a TPIC can only sink current. A 74HC595 can sink and source.

Draw a diagram of one (or two) complete 595 circuits that you plan to use.
Post it, so we can check before you build.
Leo..

Go Up