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ADS1293 sample rate change

Accel Abarca
Intellectual 270 points
Other Parts Discussed in Thread: ADS1293EVM, ADS1293

Hello!

I have the ADS1293EVM and I am trying to change the sample rate of CH1. I go to "Data" tab an there I change the default data of 853sps to 500sps (bandwidth 170Hz both), after that I run the simulation. After that I verify the number of samples in 1 second and I still have 853 data in 1 second. I have tried many things to change it but I still do not have success.

If somebody knows who to do it correctly, please let me know.

Regards

Accel Abarca

  • 0
    TI__Expert 3835 points

    Hi Accel,

    Click on the "Digital Filter" block of CH1 in the block diagram to configure its decimation ratio (which defines the sampling rate and bandwidth); use tables 5 through 8 in the datasheet to find the corresponding output data rate and bandwidth per decimation rate setting. By default, the device's state is represented by table 5.

    The values in the "Data" tab are indicators only and they are updated when the decimation rate changes in the block diagram.

    Best regards,

    Sergio

  • 0 in reply to Sergio
    Intellectual 270 points

    Hi Sergio,

    Thank you for the answer. Now I can change the sample rate as I want.

    Regards

    Accel

  • 0 in reply to Sergio
    Intellectual 270 points

    Hi Sergio,

    The ADS1293EVM works fine and I think that I have learned how to configure and to use the ADS1293EVM software. 

    Now I am wondering if there is any chance to flash the board via ADS1293EVM software? For example, the board always is giving data as soon as somebody turns on.

    I would like to have data from the board all the time when I turn on. Could you recommend something please?

    I am looking for information about this and I found the MSP430 USB debugging interface. It seems that this tool does the thing that I want (I am still reading the datasheet).  

    On the other hand, I am using the board in shorted input configuration and I want to enable the others two input. In the configure channel tab I change the configuration of the POS2, NEG2, POS3 nad NEG3, enabling all but when I connect a differential sensor in one of these two inputs I do not watch any signal, actually I just see one screen (channel 1) in the measurement tab.

    Regards

    Accel Abarca

  • 0 in reply to Accel Abarca
    TI__Expert 3835 points

    Hi Accel,

    I'm glad to hear the EVM is working fine now.

    I'll start with your second question. There is a channel configuration register (CH_CNFG - 0x2F) where channels to read in streaming mode are enabled. The MSP430 reads from the ADS1293 in streaming mode; look for the Streaming section in the datasheet for more info. In the EVM software, you can configure this register in the Digital tab, or in the Read Back block inside the Digital Control and Power Management block. Enable E1, E2 and E3 for data read back.

    Now to your first question. The default register settings of the ADS1293 at start-up are not in conversion mode. If you want the ADS1293 in a predefined state, the MSP430 should be reprogrammed to configure the registers of the ADS1293 the way you want at start-up. How do you intend to use this mode of data always on?

    Updating the firmware of the MSP430 is not possible from the EVM software. You'll need a flash programmer tool like the FET-PRO430. See this post: http://e2e.ti.com/support/data_converters/precision_data_converters/f/73/p/232127/952172.aspx#952172

    There is also a Firmware Upgrade Tool available that can be downloaded from the USB Collateral Installers section of the MSP430 USB Developers Package: http://www.ti.com/tool/MSP430USBDEVPACK

    Click on "Get Software" >> Scroll down to USB Collateral Installers >> Download and install "MSP430_USB_Firmware_Upgrade_Example-x.x.x.-Setup.exe"

    Those are the methods that I know of. As far as development tools, you can download evaluation versions of CCS or IAR from TI's Microcontrollers page.

    Hope this information helps getting started. There is also plenty of documentation out there to check out wrt MCUs.

    Best regards,

    Sergio

  • 0 in reply to Sergio
    Intellectual 270 points

    Hi Sergio,

    Thank you for the answers.

    I could enable E2 and E3 inputs and it works. There is something that I noticed when I save the data via "Save plot as text or image" button, It just saves the channel1 and not the three channels. Is it possible to configure this to save all channels?

    About your question,  how do you intend to use this mode of data always on? I need the three channels working simultaneously for long periods of time (2 months), I could take these data via SPI or another format. I want to connect the ADS1293 board to a microcontroller which can proccess the data and save it in a masive storage.

    I will check the info that you provided me.

    Regards

    Accel

  • 0 in reply to Accel Abarca
    TI__Expert 3835 points

    Hi Accel,

    I seem to remember that the data was saved into the text file according to the number of channels that you plot, so all the data from your 3 channels should be there. Can you scan through the file, the data may be appended at the end and not to the side.

    The startup settings of the ADS1293 can only be changed after power-on by a micro or similar through the SPI interface, and by default, the device is not converting data (inputs are disconnected too). The EVM software loads a configuration file and writes to the ADS1293's registers with a 3-Lead ECG configuration.

    In a similar way, your microcontroller would configure the chip at startup with the register settings that you need and enable data conversion, and then it should go and read the data through the SPI bus.

    Regards,

    Sergio