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no response from SPI read test sequence - ADIS16448

Question asked by tjefferson08 on May 15, 2014
Latest reply on Jun 14, 2014 by NevadaMark


Micro: TI MSP430 (CC430 package)

Setup: custom PCB, scoping a fly-wired header which includes all four SPI pins, VCC, and GND.

Scope: Agilent MSO-X 3014A Mixed signal O-scope, digital probe


I'm just trying to get the SPI test read sequence to return the product ID: 0x4040.


For all figures:

D0 - nCS

D1 - SCK




The first problem I've encountered is that, at least for the MSP430, the SPI mode 3 (CLKPOL = 1, CLKPHA = 1) yields a waveform which does not coincide with the ADIS16448 datasheet's indication (page 11, section SPI Read Test Sequence). This is detailed in the first two figues (same capture, different zoom). Notice that the first positive edge on the data line comes at the first positive edge on the clock, rather than the subsequent negative edge (most evident in scope_2.png)


Then, if I set CLKPHA to 0, I get the waveform exactly as indicated in the datasheet (page 11), but I still get no 0x4040 from the MISO line. Please consult the second pair of figures (3rd and 4th) to confirm.


I have tried at 32kHz and 500kHz, with hopes that the 32kHz was simply too slow to register successfully (despite the specifications in the datasheet which allow for .01MHz/10kHz clock speed). Notice the (now) correctly delayed positive edge on the MOSI line (see scope_4.png)


Is there something obvious for which I have failed to account?