HM-10 Bluetooth Module problem / wireless EMG transfer

[aeytr]

Hello,

I have a EMG circuit with 3 electrodes. I wanna send the EMG signal via bluetooth. and I am using HM-10 for that purpose.

At first, I have to say that I can broadcast a signal which is the voltage alteration on potetiometer. (Relevant circuit is given below.) That was just a test circuit to see if my program on CC2540 is working or not.

But, when i'm triying to send the EMG signal on the output, circuit stops working. All i can see on oscilloscope is a noise.

Do I have to use a different connection type between HM-10 and EMG circuit? For now I'm connecting the EMG output directly to pin 28.(Actually ı've tried connecting EMG output via resistor or grounding EMG output with resistor before HM10 connection. Didn't worked.)


Regards.


Also pin 23 and 24 are connected as described in datasheet and relevant sources.

 

[andre_luis]

I can broadcast a signal which is the voltage alteration on potetiometer

Although the wireless medium is intrinsically prone to losses, I would not consider implausible that perhaps this problem is more related to programming than properly to the hardware scope. For example, you may be sending negative values treated in variable unsigned, or even values scaled to out of the magnitude of the variable.

Another aspect to consider is that if the transmission rate is greater than the receiver's capacity, data packets will be oversampled, therefore will be lost. Keep in mind that a prerequisite of such a system is that the sampling/displaying rate of the paired transmitter/receiver must be the same or smaller, at a constant value; it is also advisable to have a routine able to identify the sequence of each packet received - even if it have to perform a buffering - in order to detect losses.

 

[aeytr]

Although the wireless medium is intrinsically prone to losses, I would not consider implausible that perhaps this problem is more related to programming than properly to the hardware scope. For example, you may be sending negative values treated in variable unsigned, or even values scaled to out of the magnitude of the variable.

Thanks for reply,

I think the problem is the crcuit connection. Because when I touched the EMG signal output pin to HM10, I cant see anything on the EMG circuit output. All I can see is zero avarage noise that is what I get from bluetooth signal, all zeros. Actually bluetooh module broadcasting what it gets from the input pin.

Another aspect to consider is that if the transmission rate is greater than the receiver's capacity, data packets will be oversampled, therefore will be lost. Keep in mind that a prerequisite of such a system is that the sampling/displaying rate of the paired transmitter/receiver must be the same or smaller, at a constant value; it is also advisable to have a routine able to identify the sequence of each packet received - even if it have to perform a buffering - in order to detect losses.

I thought that too. It should be in acceptable range. CC2540 has 12 bit ADC. I also used the same circuit with arduino -for term project- and it was working. Only differance was there was an arduino pro mini between EMG circuit output and HM10.

Thanks for reply, I will consider your answer.

Regards,
Ali.

 

[andre_luis]

I think the problem is the crcuit connection. Because when I touched the EMG signal output pin to HM10, I cant see anything on the EMG circuit output

So, this question seems like recalling the other thread you've opened concerning to the same issue, is that ?

• https://www.edaboard.com/threads/352592/

 

[aeytr]

So, this question seems like recalling the other thread you've opened concerning to the same issue, is that ?

• https://www.edaboard.com/threads/352592/

No,that was an ECG circuit. Circuits are similar but this is not about it.