ADS8332 - Help for using this converter

Gigi DSP

Other Parts Discussed in Thread: ADS8332

Hi,

Can you provide me a block diagram for using ADS8332? I connected the ADS8332EVM to a DSP via wires for controlling the SDI, SDO, CONVST, CS, EOC and SCLK. Still, the timing diagrams don't work for me because I can't get a valid result after reading the conversion bits.

How should I set those signals to get valid data?

Please, help me! Thanks.

over 13 years ago

0 Tom Hendrick over 13 years ago

TI__Guru**** 181521 points

Hi Gigi,

In your previous posting about the ADS8332, I thought you had the timings down:

http://e2e.ti.com/support/data_converters/precision_data_converters/f/73/p/198101/706411.aspx#706411

Is it possible to send us a screen shot of your communication lines? What processor are you using and how long are the wires between the boards?

0 Gigi DSP over 13 years ago in reply to Tom Hendrick

Prodigy 70 points

Hi Tom,

It is a 5cm (2inches) long ribbon cable. I alternated the wires GND-SIGNAL-GND-SIGNAL....-GND to shield the signals. My DSP is TMDX5505EZDSP.

0 Rafael Ordonez over 13 years ago in reply to Gigi DSP

TI__Expert 6925 points

Hi Gigi,

Do you have revision C of the TMDX5505EZDSP with the 2x30 port expander?

Regards,
Rafael

0 Gigi DSP over 13 years ago in reply to Rafael Ordonez

Prodigy 70 points

Hi Rafael,

Yes, I have revision C with 2x30 port expander.

Should I use the I2C pins for SDI and SCLK? SDO can be read using an GPIO pin?

Thanks,

Gigi.

0 Rafael Ordonez over 13 years ago in reply to Gigi DSP

TI__Expert 6925 points

Hi Gigi,

SCLK, SDO, SDA, and /CS should be connected to the corresponding SPI pins of the TMDX5505EZDSP as follows:

Any two pins from GPIOs4-5 or GPIO10-17 can be used for CONVST and EOC.

I2C pins shouldn’t be connected to any pin of the ADS8332.

Regards,
Rafael

0 Gigi DSP over 13 years ago in reply to Rafael Ordonez

Prodigy 70 points

Hi Rafael,

Many thanks for the schematic. I have resoldered the connection cable to correspond to the pins indicated in the schematic.

Now I have another problem: How can I use the SPI of the DSP to communicate with the ADC? So far I only know to work with GPIO pins.

I have found one example of using SPI in C:\Program Files\Texas Instruments\ccsv4\emulation\boards\usbstk5505_v2\c55xx_csl\ccs_v4.0_examples\spi\CSL_SPI_Example but it doesn't help me because it communicates with the EEPROM of the EVM board. I want to use the SPI pins to communicate with an external device (ADS8332). In that example I only see the CS0 signal and the pin is CS1. The Rx,Tx and CLK aren't available to command or I don't see how to use those pins.

Thanks,

Gigi.

0 Rafael Ordonez over 13 years ago in reply to Gigi DSP

TI__Expert 6925 points

Hi Gigi,

You should be able to find the enumerators for configuring the SPI in the following path of the Chip Support library installation folder:

doc\csl_api_html\group__CSL__SPI__ENUM.html

To use CS1 instead of CS0, just change:

hwConfig.csNum = SPI_CS_NUM_0;
to
hwConfig.csNum = SPI_CS_NUM_1;

The SPI interface just needs to be configured. It takes care of Rx, Tx, and CLK timing from the configuration registers. Then, you just read or write data using the CSL functions keeping an eye on the flags.

To understand the configurations in detail read the C5505 SPI user guide (sprufo3):
http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=sprufo3&fileType=pdf

By the way, don’t forget to use:

hwConfig.wLen = SPI_WORD_LENGTH_16;

Regards,
Rafael

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ADS8332 - Help for using this converter