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Original question:

TMS320C6748: SPI1 Enable Pin

ADS8363EVM: Interfacing to the TMS320C6748 (C6748 LCDK)

Brian Dougenik
Prodigy 160 points
Part Number: ADS8363EVM
Other Parts Discussed in Thread: TMS320C6748, ADS8363, , ADS8361, TMS320F2812

Hello,

I am trying to interface the TMS320C6748 to the ADS8363 EVM using the SPI1 pins. I want to utilize the enable pin for handshaking with the ADC but can not find it on J15 or J16 headers. I also need a way to trigger the RD and CONVST bits on the ADS8363 but can not figure out how to do so. My thought process so far is to use one of the CS pins as a GPIO that will toggle the RD and CONVST bits right before I actually transmit the data. I am not looking for an in depth explanation on how to do this but a simple description on the process would be extremely helpful. Thank you. 

  • 0
    TI__Guru**** 168485 points
    Hi Brian,

    You have me at a disadvantage here since I have no idea what you mean by the J15 or J16 headers. Can you tell us what hardware you are using with the ADS8363EVM? The ADS8363 does not really follow a standard SPI interface, if you have access to a McBSP port, that might make your life a bit easier here. Let me know what you are working with on the TMS320C6748 side of things and we'll go from there.
  • 0 in reply to Tom Hendrick
    Prodigy 160 points
    Hello Tom,

    The J15 header is an expansion port located on the bottom of the C6748 LCDK and contains all pins necessary for SPI0. The J16 header is a 36 pin FFC camera port which contains all pins necessary for SPi1. The DSP does have a McBSP but I have absolutely no knowledge of that peripheral and what it does. Is there a starterware example for this peripheral or any examples online that use it to communicate with an external codec?
  • 0 in reply to Brian Dougenik
    TI__Guru**** 168485 points

    Hi Brian,

    I'm looking over the schematic for the C6748 LCDK, and they don't bring out the McBSP to any specific header unfortunately, so I doubt anyone on the DSP side of this has starter-ware for that peripheral. When you go through the ADS8363 datasheet, you see that the RD input needs to be qualified by a clock strobe, which is why it makes it tricky to use that part with a simple SPI port.  You could do it with GPIO and bit-banging but that's going to hamper getting speed/throughput and working with DMA.  What sort of application are you working on?  The ADS8363 is not really a codec, so maybe there is a better device to look into here.

  • 0 in reply to Tom Hendrick
    Prodigy 160 points
    Hello Tom,

    The ADS8363EVM was chosen to allow us to sample frequencies higher then what is already supplied by the LCDK so I apologize if I used the word codec in the wrong context. The LCDK currently samples at 96Khz and my customer wants higher then this. As for your suggestion on bit banging, I am not sure how I would implement that or the steps I need to take. I am an electrical engineering senior at the University so I apologize for my low level knowledge of software methods. My first question would be if I preform bit banging do I need to do it for the whole peripheral or can I still use some of the API's like SPITransmit in the SPI starterware?
  • 0 in reply to Brian Dougenik
    TI__Guru**** 168485 points
    Hi Brian,

    Please take a look at the ADS8361 instead of the ADS8363. The ADS8361 does not have any programmable registers and there are a couple application notes showing how to get this part to work with a standard SPI interface. From the ADS8361 product folder, click on the Technical Documents tab and then scroll down to Application notes. Look at the Interfacing the "ADS8361 to TMS470 Processors", "Using the ADS8361 with the MSP430 USI port" and/or the "Interfacing the ADS8361 to the TMS320F2812 DSP". These have code snippets with them as well - when you see 'Multiple Files' as the type, click on the Read Abstract link. They should give you an idea on what you need to do.