ADS1293EVM: Questions for ODR setting and data sampling speed

Prodigy 60 points

Replies: 7

Views: 90

Part Number: ADS1293EVM

Hi,

I am finding optimal register configuration for my application, and I got a problem that I cannot understand.

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With the default 3-lead configuration (R1_RATE_CH1=4, R2_RATE=5, R1_RATE_CH1=6, R2_RATE_CH1=4, R2_RATE_CH1=6), ADS1293EVM seemed to read data in normal speed.

In detail, it took almost accurate 60 sec for data read with Capture Mode: Acquire for 60 sec.

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However, when I changed the digital filter setting (R1_RATE_CH1=4, R2_RATE=8, R1_RATE_CH1=16, R2_RATE_CH1=4, R2_RATE_CH1=128), ADS1293EVM red data abnormally fast.

It took just about 40 sec for data read with Capture Mode: Acquire for 60 sec.

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What's the problem in this case? What registers should I reconfigurate to make the module to work normally?

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In addition, I found sometimes the whole acquired data do not displayed but the last 1 or 2 sec of data when I run the EVM with Capture Mode: Acquire, so that I cannot save them.

It seems to be depend on the digital filter register setting. Do you have any idea in this situation?

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Thank you,

7 Replies

  • Hi Namho,

    Can you please clarify the digital filter setting for both of the tests that you are doing? I only see R1 and R2 decimation rates setting but not the R3 setting. 

    For your second test where you are having capture issue, can you please check to see what is your Data Ready Pin Source setting in this case? (See datasheet Fig. 69 for the DRDYB_SRC setting). You can set the DRDYB_SRC register based on what you intend to capture either PACE or ECG. 

    Thanks

    -TC

  • In reply to TCT:

    The ODR setting for the 3rd channel is below:

    R1_RATE_CH=8, and R3_RATE_CH3=6

    This setting was kept in both cases (default 3-lead configuration, and reconfiguration by myself).

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    The DRDYB_SRC is 001000: CH1 ECG.

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    Thanks,

  • In reply to Namho Kim:

    Hi Namho,

    It is still unclear to me what you intended to do with the different decimation rates for the programmable digital filter in your application. Below are some suggestions that you may find useful.

    Please refer to section 8.3.7 in the datasheet for how to set the programmable digital filters for each channel and also the corresponding ODR rate for these setting in Table 8,9,10 and 11. These tables will also show the different mode of operation that allow you to optimize the performance and power consumption as required by your application.

    There is also a some clear example in the datasheet on how to set these registers values for different ECG applications (see Section 9.2). Please let us know if you are able to use the information provided above for your application setup. 

    Thanks.

    -TC 

  • In reply to TCT:

    Thank you for your reply.

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    What I mean was, ADS12936EVM acquired data with abnormally fast speed when I changed the ODR setting.

    With default 3-lead configuration, it seemed to acquire data normally.

    However, when I changed the ODR to be low, then the module acquired data too fast. It finished acquiring 60-sec data within just 40 sec.

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    Thanks,

  • In reply to TCT:

    I tried to acquire data with default 3-lead ODR setting (R1_RATE_CH1=4, R2_RATE=5, R1_RATE_CH1=6, R2_RATE_CH1=4, R2_RATE_CH1=6),

    with either FS_HIGH_CHx=0 (clock frequency=102.4kHz) or 1 (clock frequency=2014.8kHz).

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    Data acquisition speed was normal with FS_HIGH_CHx=0, but it was too slow with FS_HIGH_CHx=1.

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    I understood that FS_HIGH_CHx is responsible for resolution of the acquired data and power consumption, but not for data acquisition speed.

    Is it misunderstanding?

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    One thing I am doubtful is that the sign for BATLOW in measurement tap is green, so that the EVM might not work normally.

    Thank you,

  • In reply to Namho Kim:

    Hi Namho,

    I'll check with the team and get back to you soon. Thanks.

    -TC

  • In reply to TCT:

    Hi Namho,

    I see what you are referring to with the data capture issue other than the default ODR setting. There seems to be some inconsistency in how the data capture is implemented in the software GUI. I have no solution for you currently but I'll investigate this further and will let you know if I can find out more on this subject. 

    Thanks for your patience.

    -TC