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reading speed

Open agentff6600 opened this issue 4 years ago • 7 comments

Hi!

I might have a question that seems very obvious for you. But I guess I need to ask somebody.

I have a hard time to figure out what the update speed is. When I plug in the Arduino and look at the serial monitor (or your Gui) it seems like that the data is sent in 1 sec burst.

Is that correct? How could I change that speed?

agentff6600 avatar Sep 24 '20 10:09 agentff6600

Did you get it? How to change the speed?

Maximum20 avatar May 27 '21 18:05 Maximum20

Hi,

You meant the speed at which the ECG signal is streamed ? It samples the data in every 8ms (It is configured with a sampling rate of 125 Hz), and sends it in real time. as you can see in the arduino plotter example, it sends the data serially in every 8ms.

Why do you want to increase the speed ?

joicetm avatar May 27 '21 18:05 joicetm

Sorry, I don't need to change the speed actually, I need to increase the sample rate because the signal is not detailed enough. Can I do it?

Maximum20 avatar May 27 '21 19:05 Maximum20

Yes,

It has 3 different sampling rates possible, (128, 256, 512). you can do this by writing to CNFG_ECG Register Screenshot from 2021-05-28 09-17-02

There is a function in the library to set the sampling rate, call this after max30003_begin()

void MAX30003::max30003SetsamplingRate(uint16_t samplingRate)

It is not tested but you may try it out. you will also have to adjust the delay in the loop according to the configured sampling rate.

joicetm avatar May 28 '21 03:05 joicetm

fyi,

You can increase the gain also If you are looking to increase the signal quality. The default gain in the example configuration is only 20.

joicetm avatar May 29 '21 04:05 joicetm

@joicetm I've tried MAX30003_Reg_Write(CNFG_ECG, 0x805011); If I get right 0x805011 (11) mean to set ECG channel Gain to 160V/V isn't it? I get more information from the signal but I notice that some heart beats still don't appear on the graph .

if i use MAX30003_Reg_Write(CNFG_ECG, 0x005011); I get more noisy signal And what does the gain mean? How does it work?

Maximum20 avatar May 29 '21 08:05 Maximum20

No, Its in binary, you will have to write the corresponding hex/decimal value.

Please try 0x835000 for 128 sampling rate and 160 gain. Keep the hpf and lpf as it will help to reduce the noise.

joicetm avatar May 31 '21 07:05 joicetm