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NO ACTIVITY ON DATA BUS DURING WRITE OPERATION

shijesh ak
Prodigy 150 points
Other Parts Discussed in Thread: TMS320F28335

Hi all,

I have made a customized board using the TMS320F28335 processors. The problem which I am facing is quite strange. Before going to the issue let me take a minute in explaining the my boards configuration. The board has got two external devices connected on the external bus( XINTF)  an A/D convertor & a Ext UART.

 I have configured my ckt so that only one device remains active on the bus either the A/D or the UART. 

Now coming to the issue.

On the A/D converter I perform a 16 bit read operation only which is working fine.

But when I perform a Write operation on the UART I don't see any activity on the data lines whereas the address and other control line behave normal. To take away the effect of my external circuitry I have even isolated my ckt with the DSP and tried to write on the external bus but the problem persists. NO ACTIVITY ON THE DATA BUS. can anybody explain so as to why this is happening?????

Regards

SHIJESH 

  • 0
    Guru 13185 points
    Did you check the connection?
  • 0 in reply to Maria Todorova
    Prodigy 150 points
    As I have already told that the read operation on the EXternal A/D converter is working fine with activity on the data bus. Also i have physical checked the data lines as well & found it to be okay.
  • 0 in reply to shijesh ak
    TI__Guru** 109165 points

    Hi Shijesh,

    Which Zone (chip-select) are you using for ADC and UART in this case? Also what are the addresses? Could you share the code you are using?

    Could you just try a simple write in start of the code (before read from ADC) and see if that works fine?

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    Prodigy 150 points

    Hi vivek,

    I am using zone '0' for UART(address: 0x4000) and zone '7' for ADC(address: 0x20000).

    I use a pointer to point to the said locations and then perform read or write operations on to them.

    Ya I tried the simple write OPERATION @ the start before ADC read also but that  didn't work as well. 

    Regards 

    SHIJESH

  • 0 in reply to shijesh ak
    TI__Guru** 109165 points

    Thanks Saijesh !!

    Did you also try writing to Zone 7 location? Did that work?

    Just wanted to see if issue you are facing is specific to Zone 0 only or any Zone?

    If issue is with all the Zones then if you have another device, could you try this on that as well to confirm it's not  one device specific issue?

    If possible, please share the code you are using in this case.

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    Prodigy 150 points

    Hi Vivek,

    First of all sorry for being so late. my issue was resolved with the change of the device. Now things are working fine.

    Now I am carrying out the thermal analysis of my card and I am really interested in finding out the power dissipated by the different IC's I use (mostly TI). In this regard I want some help from ur side.

    first of all I am not that sure as to how to precisely calculate the power dissipated by an IC for say SN74LVC244APW. I have used it to pass my data bus through and connect to the DSP end & the UART end.

    I am aware that the static power consumed by the IC will be equated to Vcc times the current Icc , but I don't  know how to account for the dynamic part of the dissipation into. Here I request you to guide me by sending some relevant literature or connecting me to a concerned engineer @ TI.

    Regards

    Shijesh AK 

  • 0 in reply to shijesh ak
    TI__Guru** 109165 points

    Hi Shijesh,

    Good to know it was device specific issue and you are able to get it working after changing the device.

    Regarding your other query, I'll suggest to post this on a new post with appropriate subject line to get a quick response from other experts on forum.

    Regards,

    Vivek Singh