Interfacing a Pulse oximeter with a RPI

[Charles Gwellem]

Hello dear folks,
I am a beginner with the RPI and a beginner too with computer technology. But I have been given an assignment : I need to read data from a pulse oximeter device using an RPI and display the data on a display.
How can I go about this?
I would be very grateful for any proposals.

[texy]

Hi and welcome to the forum.
It would help if you could supply a link to the oximeter, as I'm guessing that most of us will have no idea what it is or how to connect to it otherwise.
rgds,
Texy

[Charles Gwellem]

Dear Mr.Texy,
I am honored by your kind attention here is the link:
http://www.medlab-gmbh.de/english/modul ... ry/eg00352

The datasheet and technical specifications for the poximeter are found in this link under the ''download'' rubric

[ghans]

They have several , please link directly to the product page
and the datasheet.

ghans

[Charles Gwellem]

Dear Ghan,

I thank you for your attention..here is a more precise link:
http://www.medlab-gmbh.de/english/modul ... ry/eg00352

the datasheet and technical specifications for the poximeter is found in this link

[joan]

Ok thank you for your attention..here is a more precise link:
http://www.medlab-gmbh.de/english/modul ... ry/eg00352

the datasheet and technical specifications for the poximeter is found in this link

The technical pdf suggests it can communicate via the Pi's serial link. Possibly without modification as it says CMOS level and is powered from a Pi safe 3V3.

[Charles Gwellem]

Dear Joan,
I am honored by your kind attention and reply.

Do you mean I can just go ahead and connect the POX to the PI without modifiying anything? Did I get you well? If not please enlighten me more about your response.

[joan]

Dear Joan,
I am honored by your kind attention and reply.

Do you mean I can just go ahead and connect the POX to the PI without modifiying anything? Did I get you well? If not please enlighten me more about your response.

What I would do and what you should do are two separate things. You will have to read the pdfs yourself to determine whether you think it is safe or not. Perhaps a colleague at work could help?

[Charles Gwellem]

Hello Joan,
I have gone through the data sheet and the technical manual of the pulse oximeter. Please can you enlighten me on the major steps i need to carry out especially with the software aspect of the project?My project consists of displaying the pulse oximeter data on a raspberry PI.Very very few of my colleagues know about the Raspberry pi.

thanks

[joan]

Have you a working Raspberry Pi?

I would make the following connections between the Pi and the unit.

Code: Select all

Pi                   Unit
Header               JP2

pin 1 (3V3)    <---> pin 2 VCC (3V3)
pin 6 (ground) <---> pin 1 (ground)
pin 10 (RXD)   <---> pin 6 (TXD)

The following assumes you have a terminal window open on the Pi.

I would then issue the following command at the Pi to set the serial baud rate to 9600.

stty -F /dev/ttyAMA0 9600

The unit should be continuously transmitting (binary) data. Check that it is operating properly by

cat </dev/ttyAMA0 | od -x

The above command should print lots of data. Stop by pressing ctrl+C.

If you cut & paste then post some of the data it should be easy to confirm correct operation. The software to decode the binary is straightforward. Examples are in the pdf.

It should be an hour or so to write and test the software (then a couple of weeks to document and review and obey all other company procedures!).

[Charles Gwellem]

Dear Joanna,
I am extremely grateful for all your help.It is helping me alot. I have tried to type in the Source code example for protocol 2 (which is in Turbo C) into the LX Terminal of the RPI. But each time I try to save and compile, I recieve various error messages either about syntax and other features concerning the source code protocol.How can I solve this problem(i.e.the problem of entering the source code, in Turbo C, into the RPI)?

Thank you very much..

[joan]

Dear Joanna,
I am extremely grateful for all your help.It is helping me alot. I have tried to type in the Source code example for protocol 2 (which is in Turbo C) into the LX Terminal of the RPI. But each time I try to save and compile, I recieve various error messages either about syntax and other features concerning the source code protocol.How can I solve this problem(i.e.the problem of entering the source code, in Turbo C, into the RPI)?

Thank you very much..

Did you manage to get any output from the device? If so what does it look like?

[Charles Gwellem]

Hi Joanna,
I connected the serial port of theb pulse ox to the USB of the RPi using a serial to usb cable....I powered the Pulse ox with a well regulated 3V3 voltage supply...i issued the following commands in their respective order;

1)to know the name of the usb->serial adapter device on the RPi .

pi@raspberrypi ~ $ lsusb

2)I set the baudrates and other parameters using this command:

stty -F /dev/ttyUSB0 9600 cs8 -parenb -cstopb -crtscts


3) To see the out put:

cat /dev/ttyUSB0

BUT THE OUTPUT I SAW ON THE LX TERMINAL WAS A SERIES OF UNREADABLE CHARACTERS....Please how can go over?

[joan]

Look back at my post, in particular look at the cat command I suggested.

[scotty101]

There are a few problems with the test you performed.

1. According to page 9 of the datasheet Datasheet, there are 2 protocols; one uses 9600 baud and the other used 4800 baud, check which one you are using.

2. The pulse oximeter does not output in a human readable format. You need to process the data in order to decode the binary data. There are example of c code to do this in the datasheet.

Your next steps
1. Learn how to compile a basic C "Hello World" program on the raspberry pi
2. Learn how to open a serial port with C and print the raw data to the screen.
3. Use the examples in the datasheet as a starting point to decode the binary data from the pulse oximeter to grab the heart rate/oxygen levels etc.

[Charles Gwellem]

..

[mikronauts]

See http://pyserial.sourceforge.net/pyserial.html

Thank you all very much for your suggestions...But I wish to work with Python programing language, thanks to its simplicity

[Charles Gwellem]

Please can someone write a simple example code I can use to test the pulse oximeter atleast for a begining?

[joan]

Please can someone help me write a simple code I can use to test the pulse oximeter?

cat /dev/ttyUSB0 | od -x

[Charles Gwellem]

Thanks alot Joan...I tried that and it produced raw data that looked like this:
"zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz"


I am now seeking for a simple example of a program that would contain the source code on page 13 of the puls ox manual

[joan]

Thanks alot Joan...I already tried that and it produced raw data...I am seeking for a example of a program that would contain the source code on page 13 of the puls ox manual

If we had sight of the raw data we could see if the results are as expected.

[DougieLawson]

You may be able to run the C# program using Mono on your Raspberry Pi. (There's going to be an article on Mono in the next issue of the MagPi magazine, so I've got a Mono test bed set-up, my problem is not having the SpO2 hardware.)

http://www.medlab-gmbh.de/english/downl ... x2pc_c.zip

[Charles Gwellem]

we expect to see data like this unbder normal circumstances

SPO2=096% BPM=106 PI=01.68% SPCO=--.-% SPMET=--.-% DESAT=-- PIDELTA=+--

[joan]

Thanks alot Joan...I tried that and it produced raw data that looked like this:
"zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz"


I am now seeking for a simple example of a program that would contain the source code on page 13 of the puls ox manual

Are you sure? I can not see how the command I suggested could possibly result in that output.

[DougieLawson]

Thanks alot Joan...I tried that and it produced raw data that looked like this:
"zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz�J�0|zyz"


I am now seeking for a simple example of a program that would contain the source code on page 13 of the puls ox manual

When you get data like that it's normally one of two things. 1. Baud rate is wrong. 2. Protocol (start bits, stop bits, parity bits) is wrong.