Config SPI for shift registers

nmcelrath · Joined: 01 May 2014 Posts: 1 Location: Ham Lake, MN

I am programming an ATMEGA32A. I am using shift registers to display on four seven segment LED displays.
The problem;

We used an NXP part NPIC6C595PW-Q100 for years and everything worked. This part went obsolete and we substituted the Texas Instruments part number TPIC6C595PWR. Now there is no display. I have tried all the changes to the Config SPI to no avail. Any suggestions or sample code would be greatly appreciated. Embarassed

MWS · Joined: 22 Aug 2009 Posts: 2262

programmista123 · Joined: 31 Jan 2018 Posts: 141

Hi,

1. Part from Nexperia has better ESD rating, Charged-Device Model and it is 1000 V according to AEC-Q100-011 rev.B. Part from TI has 200 V, unknown rev.
2. Are parts purchased directly from Ti or an authorized distributor?

Regards,
Przemek

JC · Joined: 15 Dec 2007 Posts: 586 Location: Cleveland, OH

I'll share a thought or two, although I will acknowledge that you have probably already consider them:

Are you using the same PCBs that you used with the original chip, or did that change, also, when you changed the power shift register chip?
i.e. Is there a new PCB with an error in the layout?

Did any of the other chips / parts change with this new revision, or are they from the same parts bins, (i.e. did someone swap a common anode / cathode display for a common cathode / anode display, etc.?).

If you are using the SOIC or TSSOP packages, are you sure that they are oriented on the PCB correctly?

What's your experience with bread boarding / prototyping?
(Can you put a new driver chip on a bread board with a single LED on each 8 outputs and write a simple "ripple flash" the LEDs test program?)

If that works, can you use a stripped-down version of your present code to test the chip & LEDs, but use the same config, inits, and output routines?

JC

Alexander-Dan · Joined: 13 Mar 2014 Posts: 111 Location: S.Posad

Hello
I have used all versions of these chips for a long time.

You were asked the right questions. I would like to see part of the circuit diagram of your device, where the pins of the microcircuits and their functions are indicated.
It will be useful for analysis to see a picture of your printed circuit board from your CAD design indicating the type of chip package.

Also, please tell me at what frequency does SPI operate in your program?