Tags: allin, application, attached, communication, file, interface, labview, pdf, programming, sensore, spi, usb

NI USB 8451

On Programmer » LabVIEW

5,082 words with 6 Comments; publish: Thu, 08 May 2008 00:46:00 GMT; (20046.88, « »)

Hello All

In one of the application ,i have to interface three sensore (ple

ase see attached .pdf file) with NI USB 8451 using SPI communication.

I donot know how to interface them ,

please help

It is very urgent

Thanks and regards

ADNS 50205.pdf:

http://forums.ni.com/attachments/ni/170/202305/1/ADNS 50205.pdf

All Comments

Leave a comment...

  • 6 Comments
    • Hi,

      What problems are you having? Are you receiving errors? Here are some resour

      ces for the USB-8451.

      <a href="/app/links/?link=http://digital.ni.com/manuals.nsf/websearch/5DD35472A266690F8625709

      F0044982B" target="_blank">NI-845x Software User Manual</a>

      <a href="/app/links/?link=http://digital.ni.com/manuals.nsf/websearch/04456F32F6D2B9CB8625709

      700545149" target="_blank">USB-8451 User Guide and Specifications</a>

      <a href="/app/links/?link=http://zone.ni.com/devzone/conceptd.nsf/webmain/b380e99daad898b3862

      5710f007003c5" target="_blank">Using the National Instruments USB-8451 I2C a

      nd SPI Interface to Evaluate a Texas Instruments Analog-to-Digital Converter

      </a>

      Based on the data sheet you posted, the clock rate should be set t

      o 1 MHz. Please let me know if you have any specific questions I can he

      lp you with.

      Regards,

      #1; Thu, 08 May 2008 00:47:00 GMT
    • Hi

      Thanks for reply.

      I am using SPI communication with ADNS-5020 not I2C. I have to interface 6 s

      ensors with NI 8451 card.

      Can I capture the data simultaneously from all the 6 sensors or there should

      be some time delay between data acquisition from the any two sensors.

      Please reply as soon as possible

      Regards

      R

      #2; Thu, 08 May 2008 00:48:00 GMT
    • I don't think you can capture the motion data from all six sensors simultane

      ously using the 8541 I2C channel. The I2C is a bus and you can only address

      one slave device at a time with the 8451. To capture data from all six slave

      devices you probably will

      have to use the DIO port and bit-bang your own I2C. You'll use one of the I/

      O as clock, which can be common to all six slaves. Then each of the SDIO is

      connected to their own I/O. Since you want to address all six sensors at the

      same time you can use one

      remaining I/O line as a common slave select. Your routine will have to switc

      h the I/O from output to input after setting up the addresses to read from e

      ach of the sensor. You should use the Burst Mode as you can read continuousl

      y without sending the regsi

      ter address repeatedly, which will cause delay.

      Depends on the motion, if the velocity and acceleration are high the 8451 ma

      y not be able to keep up. Then you maybe better off by having six separate m

      icrocontroller doing the I2C communications at the hardware level with the s

      ensors and use the 8451 to

      manage the captured data.

      Hope this helps.

      New LV User

      #3; Thu, 08 May 2008 00:49:00 GMT
    • Hi

      Thanks for reply.

      As i told earlier , i am not using I2C communication but I am using SPI comm

      unication.

      So Please reply considering SPI communication not I2C.

      Regards

      R

      #4; Thu, 08 May 2008 00:50:00 GMT
    • Yes, R. I am sorry I kept thinking of I2C but the concept for SPI is the sam

      e. It's a bus and you have six slave devices. You will not be able to get da

      ta from all six slaves simultaneously using the 8451. You can have common SC

      LK, MISO and MOSI for all t

      he six slaves; but you'll have to use six separate Slave Selects (using the

      DIO) to read motion data from each sensor; one at a time. Once motion s

      tarts the sensors are going to accumulate delta x and Delta y counts. D

      epends on how much motion y

      ou are trying to record this process may or may not be able to complete

      the six sensor reads before some of the the delta x and delta y accumu

      lators overflow. At that point you begin to miss motion data. Obvi

      ously depends on your appli

      cation this may not be an issue.

      Regards,

      New LV User

      #5; Thu, 08 May 2008 00:51:00 GMT
    • Hello, R:

      I did some additional thinking of your application with six 5020 m

      otion senors. I thought of a way to read the six sensors simultaneously with

      the 8451.

      You would bus the SCLK, MOSI and Slave Select signals of the six sensor

      s together. These three signals are then controlled by the 8451 SPI port and

      one of the Slave Selects.

      Each of the 5020 sensor will have a MISO left. You'll use six DIO lines

      to receive from each of the MISO.

      When you read the motion data, you'll be reading from the same register

      s of the six sensors and so therfore you'll be able to send the register add

      ress on the common MOSI and clock with SCLK.

      Now, set up the DIO port as input and perform a port read. You'll be c

      apturing the motion data from the six 5020 simultaneously. You'll have

      to manage the accumulation of these bits, each DIO input associates with one

      of the sensors.

      Again, depends on the speed and acceleration of your motion you may hav

      e to adjust the SCLK in order to capture all the motion data.

      Hope this helps.

      Regards,

      New LV User

      #6; Thu, 08 May 2008 00:52:00 GMT