Using TPIC6B595 Shift Register

Using Arduino LEDs and Multiplexing
1

After using 74HC595 Shift registers and ULN2803’s for a while (though not always correctly XD ) I am now trying to now use the TPIC6B595 Shift registers with SPI. I have attached an image of my circuit and here is the basic code that I am starting with. I have kept the code simple until I understand how to drive the chip correctly, Can someone please tell me what I might be doing wrong because it is not working correctly. Also, I assume that the zero’s in my “digit” byte are the ones that are controlling the grounds that will light the appropriate LED’s,
Thanks Pedro.

// use SPI to control eight LED's with TPIC6B595 Shift Register

#include <SPI.h>
#define dataPin 11  // MOSI
#define clockPin 13 // SPI SCLK
#define latchPin 10 // SPI SS

byte digit = B10101010;
byte timer = 100; 

void setup() 
{
  pinMode(latchPin, OUTPUT);
  pinMode(dataPin, OUTPUT); 
  pinMode(clockPin, OUTPUT);
  SPI.begin();  
}

void loop()

{
  digitalWrite (latchPin, LOW);
  SPI.transfer(digit);
  digitalWrite (latchPin, HIGH);
  delay (timer);
}

TPIC6N~1.png
TPIC6N~1.png1115×700 5.27 KB

2

I as a databit in makes the output go low to sink cathode current, same as if driving ULN2803.
SRCLR is typically tied to 5, and OE/ tied to Gnd.
Output will appear erratic if these 2 pins are left floating.

Delete these - SPI library takes care of them
#define dataPin 11 // MOSI
#define clockPin 13 // SPI SCLK
pinMode(dataPin, OUTPUT);
pinMode(clockPin, OUTPUT);

All GNDs must be connected.
Put a 0.1uF cap from Vcc to Gnd.

3

Thanks Crossroads, I'll try that later (when I finish WORK) 8)

4

Crossroads, when you say “SRCLR is typically tied to 5 “ presumably SRCLR means pin 8 of the 595, and what does “tied to 5” mean?
And OE (output enable?) is pin ? of the SR ?
Sorry for my ignorance but I still find that there are quite a few different names for some of the pins of these IC’s
EDIT - I worked it out Tied to 5 meant SRCLR (Pin 8 of 595) to + 5V
OE is pin 9 (G overscore) of 595 to ground.
Thanks again Crossroads 8) easy when you know how

5

Yup.

6

@crossroads I configured a TPIC6b595 on a circuitboard with only pin 10 connected to GND (lower left corner given half-moon at the top) and the other GND pins unconnected. Is this a problem? What consequences might I observe and should I fix the design or is it just a nice-to-have with each GND connected to a common plane?

Currently the circuit seems to be acting as it should, but perhaps there's a failure mode associated with not having them all grounded.

By the by, overscore G is also connected for logic reasons to GND, in case my statement above is misleading.

Thanks for your help.