TPIC6B595 shift register - Can't seem to get it to work with Teensy 3.5 - do I need to set up pins?

I'm using this library to test out a TPIC6B595 on a breadboard with a singular LED... I've got the following pins connected to the Teensy:

  • Data in pin connected to pin 21 (MOSI1)
  • Clock pin connected to pin to pin 20 (SCK1)
  • Latch pin connected to pin 19
  • Data clear I've tried connecting to pin 31, but long term plan is to just connect the IC pin to 5v via a 10k resistor.

Aside from that, the IC is connected up exactly as the datasheet describes, and I have a single LED connected between 5v rail and one of the IC drains via a 470R resistor. According to every diagram I've seen, this should work without issue. I've double checked that the LED is the right way round, and tried two different ICs (both new) to no avail - the LED doesn't light...

I've just read some of this about using SPI with Teensy: SPI Arduino Library, connecting SPI devices to Teensy

I'm wondering, do I need to use any of this code to change pin modes or set up SPI in addition to the library I'm using - could that be the issue?

EDIT:

Tried adding the following but no success yet :frowning:

  SPI.begin();
  SPI.setMOSI(21);
  SPI.setSCK(20);

Are you sure ?
Is /G pulled low and /SRCLR pulled high ? You haven't mentioned these.

1 Like

Yes I think I have these right. The complete connections are:

Pin Connection
2 5V Teensy pin (vcc)
3 Teensy pin 21 (data out)
5 LED > 470R > 5v rail
8 10k > 5v (SRCLR pulled high)
9 GND (G - output enable pulled low)
10 GND
11 GND
12 Teensy pin 19 (RCK - latch)
13 Teensy pin 20 (SRCK - clock)
19 GND

It works! Turns out my breadboard has a dead spot :rage: