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BF70X PPI

Sorry very new to Analgo Device's DSP's.  Are there any examples of Blackfin processors being interfaced to parallel peripherals such as AD7651?  All the EVAL boards have a ton of glue logic in the form of a FPGA.  I assume this is not needed in a custom approach but can't find any examples.

Best,chris

  • I'm pretty new also, so I dont have alot to offer. This board seems suprisingly quiet concidering such a great device. Have you tried bit banging out the parallel pins per whatever protocol the periphial is looking for? Do you have a scope so you can look at the signals to verify what you are sending? 

  • For the AD7651 I suggest using the SPI serial interface which should be pretty straightforward.

    Try starting with one of the example projects.

  • My old system is SPI and suffers from the phase lag created by the serial clock in/out of the samples. that clock is running at 14MHz, hence the need for the PPI or bit-banged parallel bus for single cycle clock in/out of samples.  i don't need a fast bus, just the parallelism.

    AD engineers say that the PPI can't support both ADC and DAC, so its back to bit bang with GPIO.  Any suggestions there?

  • Hi Chris,

    Do you mean that you have both an ADC and a DAC in your system? If so, perhaps you would be better off using a part from the ADSP-BF60x family that has more than one PPI interface.

    If you need to stick to bit banging with the BF70x family, the General-Purpose Ports chapter of the Hardware Reference Manual can help you. Inputs such as the data signals need to be configured as GPIO inputs (PORT_FER and PORT_INEN registers) and then read from the PORT_DATA register at the appropriate time. Outputs such as control will need to be configured through PORT_FER and PORT_DIR. Writes will then need to be made to the appropriate PORT_DATA bits to toggle the pins.

    Regards,

    Joe

  • Hi Joe,

    yes i have both ADC and DAC's in my system.  I looked at the 60X series but they seem power hungry compared to the 70X series.  My system is battery operated portable.  Can you comment on the power consumption between 60X and 70X series?  Also cost is a factor and 60X were 2-3x the cost.  If i can get this parallel bus done with just a bit more overhead, i can save cycles (phase), power, cost?

    best,chris

  • Hi Chris,

    Under the same workload I expect BF60x parts will typically consume approximately 40% more power.

    Regards,

    Joe

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