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OMAP L138 UPP port - receive mode.

WENBO LI
Intellectual 440 points

Other Parts Discussed in Thread: OMAP-L138

Hi,

I would like to use the UPP port to receive 12-bit ADC data from an external ADC device. The ADC will provide the Data_Frame, Data_Clock and D[11:0] data to interface the UPP port.

In this case, I think I can just use the CHA_Start, CHA_Clock, and D[15:4] to implement the interface to ADC and configure the UPP CHA port in receive mode only. And also, in my design, I don't want to use CHA_Enable, CHA_Wait, and D[3:0] because I want to use them for other purpose such as GPIO.

I have following questions to which you may have answers.

1). Is my implementation a proper configuration? Do I need to connect the ADC 12-bit data to the least significant 12 bits of UPP data port rather than connecting them to the most significant 12 bits of UPP data port.

2). Since I don't want to use CHA_Enable, CHA_Wait, and D[3:0] to interface my ADC device,I will disable CHA_Enable using ENAx bit in UPICR.

When the CHA_Enable is disabled, does it mean the CHA channel is going to be always enabled internally?

Becasue the UPP will be in a receive mode, I wonder if I still need to disable the CHA_Wait using Waitx bit in UPICR. Maybe I don't need to disable the CHA_wait,but just need to repurpose this pin to an GPIO that I want. What's the right way to do it?

Thanks,

Wenbo

  • 0
    TI__Mastermind 20790 points

    Wenbo Li,

      The uPP can be configured to receive or transmit and also to use either 8 or 16 data lines.
      It can be done by uPP channel control register(UPCTL).
     
      Please refer the OMAP-L138 (DSP + ARM) Processor Technical Reference Manual for uPP.
      http://www.ti.com/lit/ug/spruh77a/spruh77a.pdf
     
      You can get the details about signals like Data[7:0], Data[15:8], start, Enable, Wait and Clock.(From Page: 1526)

     

  • 0 in reply to Pubesh
    Intellectual 440 points

    Thank you.

    1). Yes, I understood that the UPP port can be configured at tx/rx at a different word length (from 8bit to 16bit). My question is how I should connect the data bits to the UPP data bus - data bits to MSBs or LSBs? For example, if my ADC is a 12bit parallel data bus, shall I connect them to the 12 LSBs or 12 MSBs of the UPP data bus, or it does not matter?

    2). When the UPP is configured in receive mode, the reference manual says that the WAIT is an output, and is always driven low. My question is that if I don't use the WAIT for my UPP control, can I repurpose it to an GPIO? Or the WAIT must be kept for the use of UPP?

    Can you please clarify the above two quesitons with your TI colleagues? I cannot find the answers from the datasheet or reference manual.

    Your support is greatly appreciated.

    Best regards,

    Wenbo

     

  • 0 in reply to WENBO LI
    TI__Mastermind 20790 points

    Wenbo,

     1. The uPP data bus - data bits connected to MSB.
        How to connect the uPP with ADC or DAC interface, refer the below link,
        http://processors.wiki.ti.com/index.php/Introduction_to_uPP

        In DAC MSB is Bit1, See the pin configuration in the below link,

        http://www.ti.com/lit/ds/symlink/dac900.pdf  

    2. If uPP is configured as a receive mode, WAIT signal is an output and driven low.
        For example if you configured channel "A" for receive mode, it will act as below
      
        If 0 WAIT signal is disabled. Channel A ignores WAIT in transmit mode.
        If 1 WAIT signal is enabled. Channel A honors WAIT in transmit mode.
      
        Refer the uPP Interface Configuration Register (UPICR) in OMAP L-138 TRM or uPP user manual.
        http://www.ti.com/lit/spruh77
        http://www.ti.com/lit/sprugj5