Interfacing ADS7881 with OMAP-L138 EVM

Tariq Siddiqui

Other Parts Discussed in Thread: ADS7881, OMAP-L138, ADS7881EVM

Hi,

ADS7881 offers parallel interface, I am wondering if it's possible to interface this data converter with OMAP-L138 EVM using UPP ? What other options are available to interface this device with OMAP-L138 ? The idea is to have PING PONG buffer scheme to continue sampling and processing of data.

Any example code to start the development will be highly appreciated.

Regards,

Tariq

over 12 years ago

0 Tom Hendrick over 12 years ago

TI__Guru**** 174266 points

Hi Tariq,

Unfortunately we do not have any example code that might be useful for the ADS7881 with the UPP of the OMAP-L138.

0 Christopher Hall over 12 years ago in reply to Tom Hendrick

TI__Mastermind 44620 points

Tariq,

All I can recommend is to check out this resource: http://processors.wiki.ti.com/index.php/Introduction_to_uPP

I am not familiar with the uPP interface, but it's description shows that it is intended to be used with high speed ADCs:

"Benefit: The uPP module performs parallel data transfer using two independent channels at speeds up to 75 MHz. The peripheral includes an internal DMA controller to minimize CPU and/or EDMA overhead. The uPP protocol is designed to interface simply with high speed digital-to-analog converters (DACs) or analog-to-digital converters (ADCs), and it can also be used for high-speed data transfer to or from an FPGA or uPP-equipped DSP. Clock speed, signal polarity, and transfer size are all configurable on a per-channel basis."

(taken from http://processors.wiki.ti.com/index.php/C674x/OMAPL1x_Introductory_Information#What_peripherals_are_available_with_C674x.2FOMAPL1x.3F)

Regards,
Chris

0 Tariq Siddiqui over 12 years ago in reply to Christopher Hall

Expert 2270 points

Tom, Chris,

Thanks.

Can you please help me interfacing above mentioned ADC with OMAP-L138. I understood that there is break out board available from third party which can be used for communication with outside world. There are some codes available to exercise UPP peripheral to transfer data from ADC. What I don't understand is how to drive ADC ?

I have ADS7881 EVM which I want to use with OMAP-L138 using UPP for fast data transfering and processing.

Regards,

Tariq

0 Tom Hendrick over 12 years ago in reply to Tariq Siddiqui

TI__Guru**** 174266 points

Hi Tariq,

The UPP does not have the /RD or /WR strobes that you would normally find on a more traditional parallel bus like (for instance) the EMIF on the TMS320C6713. The ADS7881 needs a CONVST input, which you might be able to get from a timer or GPIO output from the L138. The UPP though would need a clock from the ADS7881EVM which is not present, there is an internal conversion clock on the ADS7881, but it is not available outside the chip. You might be able to use BUSY from the ADS7881 as the START input to the UPP, but again, there is no means to clock the data through. You'd have to add that functionality somehow to the ADS7881EVM.

0 Tariq Siddiqui over 12 years ago in reply to Tom Hendrick

Expert 2270 points

TOM,

Thanks for your input.

Understood but it should be possible to interface ADS7881 without UPP ? Any other high speed EVM which is possible to interface with OMAP-L138 using UPP ?

Thanks.

0 Christopher Hall over 12 years ago in reply to Tariq Siddiqui

TI__Mastermind 44620 points

Hi Tariq,

There aren't any other parallel inputs available on the OMAP-L138. I don't see a way to interface to the ADS7881 using the OMAP-L138, because you would need a common clock source.

I did find this resource page: http://processors.wiki.ti.com/index.php/C6748/46/42_Complementary_Products

It shows a list of ADCs, DACs, and clocks that you could use with uPP. Here is the list of ADC's that would work with the uPP interface:

Regards,
Chris

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Interfacing ADS7881 with OMAP-L138 EVM