Bus width setup when using AN75779 Application Note

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MoAb_1070241
Level 1
Level 1

I have looked at the AN75779 Application Note, and there is some confusion over the bus width setup, as explained below:

The GPIF II interface is setup for an 8-bit data bus, but the uvc.c code shows the IO Matrix being setup as shown below:

/* Configure the IO matrix for the device. */

io_cfg.isDQ32Bit        = CyTrue;

io_cfg.s0Mode          = CyFalse;

io_cfg.s1Mode            = CyFalse;

io_cfg.lppMode          = CY_U3P_IO_MATRIX_LPP_DEFAULT;

io_cfg.gpioSimpleEn[0]  = 0;

io_cfg.gpioSimpleEn[1]  = 0;

io_cfg.gpioComplexEn[0] = 0;

io_cfg.gpioComplexEn[1] = 0;

io_cfg.useUart          = CyTrue;   /* Uart is enabled for logging. */

io_cfg.useI2C           = CyTrue;   /* I2C is used for the sensor interface. */

io_cfg.useI2S           = CyFalse;

    io_cfg.useSpi           = CyFalse;

Why is isDQ32Bit set to CyTrue when the GPIF II interface is setup for 8-bit? I am guessing that the setting in io_cfg is somewhat disjoint from the GPIF II setup in that one can set the isDQ32Bit to “true” and use any allowable data bus width within GPIF II. Could someone shed some light on this for me?

Thanks,

Mo

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1 Solution
Anonymous
Not applicable

Hi,

Yes, your understanding is correct.

Also, please note that it is not true the other way round (i.e if you set isDQ32Bit = CYFalse, you cannot set the GPIF to 8 Bits)

Regards,

- Madhu Sudhan

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2 Replies
Anonymous
Not applicable

Hi,

Yes, your understanding is correct.

Also, please note that it is not true the other way round (i.e if you set isDQ32Bit = CYFalse, you cannot set the GPIF to 8 Bits)

Regards,

- Madhu Sudhan

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Thanks,

I don’t understand your comment “Also, please note that it is not true the other way round (i.e if you set isDQ32Bit = CYFalse, you cannot set the GPIF to 8 Bits)”. I thought that if isDQ32Bit = CYFalse, then I can set the GPIF to 8 or 16 bits.

Please elaborate on your comment, and explain what bus width can be selected on the GPIF when isDQ32Bit = CYFalse.

Regards,

Mo

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