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ringram2077

Expert Boarder

2006/12/13 09:35

SSI Hardware Question

I need to setup the hardware SSI to interface to a SPI device. How exactly does the SSIFss pin play into the operation ? As I understand it, the SSIFss pin connects to the CS of the SPI device. One example I saw took this pin low to access the device. Is this the correct mode of operation or does the SSIFss pin toggle the SPI device automatically ? Also, is SSI_FRF_MOTO_MODE_0
the correct protocol (the one used in the example). ?
Thanks

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ringram2077

Expert Boarder

2006/12/21 17:14

Re:SSI Hardware Question

I'll try to answer my own question based on things I have learned since the post.

The SSIFss pin is used to select the SSI(SPI) device. Take the pin low to select the device, then take it high to deselect the device.

The mode of operation depends on what the device wants to see. It appears that for the SPI protocol you will use either MODE_0 or MODE_3. The LM3S811 manual shows detail timing diagrams for each mode (0, 1, 2, and 3).

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ringram2077

Expert Boarder

2006/12/21 17:15

Re:SSI Hardware Question

I'll try to answer my own question based on things I have learned since the post.

The SSIFss pin is used to select the SSI(SPI) device. Take the pin low to select the device, then take it high to deselect the device.

The mode of operation depends on what the device wants to see. It appears that for the SPI protocol you will use either MODE_0 or MODE_3. The LM3S811 manual shows detail timing diagrams for each mode (0, 1, 2, and 3).

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