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SPI: Noise on MISO pin using ADAS1000SDZ

Question asked by samyukta on May 27, 2015
Latest reply on May 27, 2015 by samyukta

Hello all,

I am using a Freescale K53 Kinetis Microcontroller to talk with an ADAS1000SDZ. I have written the SPI code to set the registers as required and on scoping, am observing the chip select, clock and data on the Master out pin (MOSI) line correctly.

However, the signal on the MISO pin is very noisy and hence the data that I receieve from the ADAS is garbage. I have verified that it is not a wire or connector problem by checking the signal coming out directly from the ADAS1000 at two points : namely, the MISO pin on the J4 header, and the T2 pin which both give the MISO output. Both give the exact same output, which is noise.

I am fairly sure the software part is correct, that is what should be done in code has been done as the output is as I expect it to be.

What could be the problem with the MISO line?

Also, I have checked the IOVDD, AVDD and AGND signals on the board and have confirmed that they are as they are supposed to be according to the datasheet. Also, the entire thing works well with the Blackfin DSP SDP board provided with the AFE.

I had earlier pulled up the PDB pin on the J4 header. I have kept the jumper positions as required to use the SPI interface (L12 open, L14 closed according to the ADAS1000 datasheet).

What else can I do to get a proper data signal from the slave?

 

Message was edited by: Samyukta Ramnath

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