LM3S8962 : SPI clock problem

[Poulpy314]

Hi

I'm working on a project using the Luminary LM3S8962 Evaluation kit and a 4-channel Analog Digital Converter 24 bits from Texas Instruments ADS1274EVM.

I want to get data sent by the ADC with the LM3S8962 using the SPI bus. 

I adapated the example provided by the following link for my case : http://decibel.ni.com/content/docs/DOC-7701

The ADS1274EVM provides 2 pins for SPI communication : DOUT1 and SCLK.

When it gets a clock on the SCLK pin, it starts sending data through DOUT1 pin, there is no Slave Select pin.

If I'm right, I only have to connect :

- the SSICLK pin of the LM3S8962 with the SCLK pin of the ADS1274EVM 

- the SSIRX pin of the LM3S8962 with the DOUT1 pin of the ADS1274EVM.

The ADS1274EVM is power supplied independently from the LM3S8962, so I don't connect VA VIN GND as indicated on the page  http://decibel.ni.com/content/docs/DOC-7701.

I'm posting because it doesn't work : the ADS1274EVM doesn't send data since I didn't manage to get a clock signal from the SSICLK pin of the LM3S8962 which enables the ADS1274EVM to start conversion

I believe that the "ARM SPI Create Configuration Reference VI" configures a clock that is send through the SSICLK pin of the LM3S8962, but it doesn't work as expected.

Can someone help me please? Thanks

Luc Y.

[Olivier_L]

Hi Luc,

What sounds strange for me, even if I'm not a specialist in SPI communications, is that your ADC doesn't need a Chip Select signal.

In that way, what have you set on the "ARM SPI Create Configuration Reference VI" as chip select input?

Maybe there is something going wrong when you assert a wrong line as a chip select...

I'll try to get a LM3S8962 to test the SPI communication.

Regards,

[Olivier_L · Accepted solution]

Hi Luc,

I just tested the example and had no problems generating a Clock on SSICLK.

I attach the project I did with LV 2009 SP1. I hope you could test it and tell us if it works.

Regards,

[Poulpy314]

Hi Olivier

I just tested the project with another kit and I managed to get a signal on the SSICLK pin....

I thought it was a problem with Labview but it seems my first kit had some little problems...

thanks anyway! 

Luc Y.