Advice on selecting perfect items for this project (Beginner)

Hi guys,

i needed to transfer temperature and accelerometer data through wireless(WiFi or Bluetooth) to my PC. and separately i needed to transfer heartbeat rate data through wireless (WiFi or Bluetooth) to my PC. battery usage must work at least 8-9 hours. items( sensors , boards and batteries etc..) must small and durable. please advice me to select perfect items for this project(entire thing... well I'm a beginner :blush: ).
please help me.
thanks a lot. =)

i needed to transfer temperature and accelerometer data

How much data? How often? How far?

and separately i needed to transfer heartbeat rate data

Why separately?

battery usage must work at least 8-9 hours.

Then you will need a big battery. Or, maybe a small one. Definitely a round one. Unless you like square. One thing for certain is that it should be black. No, wait, pink. Or blue.

must small and durable

Subjective criteria. What is small on a 747 is not small on a roller skate.

please advice me to select perfect items

Based on what criteria?

I hope you have better requirements for the software side of this project.

PaulS:

i needed to transfer temperature and accelerometer data

How much data? How often? How far?

it must work continuously. 3-4 feet from pc

and separately i needed to transfer heartbeat rate data

Why separately?

because it's 8 feet away from temperature sensor and accelerometer.

battery usage must work at least 8-9 hours.

Then you will need a big battery. Or, maybe a small one. Definitely a round one. Unless you like square. One thing for certain is that it should be black. No, wait, pink. Or blue.

:~ i just need a small battery that support this project.

must small and durable

Subjective criteria. What is small on a 747 is not small on a roller skate.

:~

please advice me to select perfect items

Based on what criteria?

i just needed advice on suggesting sensors , boards , battery models.

I think you need to properly consider the communications. Your "separate" transfer of heartbeat implies a separate arduino and the PC thus working with two at once. This is a pivotal decision on how your project operates, yet the entire communications distance is twelve feet maximum and, on the face of it, can barely justify any wireless communication at all. If you at least had one arduino working all your sensors by cable, you will get a material simplification of the job. This would mean a simple single connection back to the PC by cable or bluetooth. The bluetooth connection costs just a few dollars and the software is unchanged from the USB connection. Using WiFi adds considerably to the cost and complexity - not to mention the battery consumption.

Nick_Pyner:
I think you need to properly consider the communications. Your "separate" transfer of heartbeat implies a separate arduino and the PC thus working with two at once. This is a pivotal decision on how your project operates, yet the entire communications distance is twelve feet maximum and, on the face of it, can barely justify any wireless communication at all. If you at least had one arduino working all your sensors by cable, you will get a material simplification of the job. This would mean a simple single connection back to the PC by cable or bluetooth. The bluetooth connection costs just a few dollars and the software is unchanged from the USB connection. Using WiFi adds considerably to the cost and complexity - not to mention the battery consumption.

thanks for reply =) i can't use cable for this project only wireless connections(wifi or bluetooth). maximum communication distance range is 3-4 feet. can you please suggest what are the models(sensors, boards, batteries etc...) that suits for this project.

Not really, as I only use bluetooth and internet myself, but your options are a lot wider than just WiFi or bluetooth. For starters, you might consider the NRF24 transceivers. They can be used in a network and have extremely low power consumption. Another is the XBee system.
FWIW I think it should be possible to use bluetooth for this but I'm not sure anybody else does. It it can be done it would probably be by having one Arduino poll the other and then send data from both to the PC.

For hardware, I can only suggest the DS18B20 temperature sensor and Arduino Unos as obvious choices, they are cheap, easy to use, and well-supported on this forum.

Your battery requirement is likely to depend as much on software, duty cycles etc. as much as hardware, and would probably be a case of suck it 'n' see.

What sort of accuracy and range are we talking about for the temperature measurements?

Just a reminder that there is no perfect solution to anything, the whole of engineering is a compromise, You have to specify things a lot more closely to allow good calls to be made on the compromises you need to make.
Some conflicting requirements could be

  1. Cost system
  2. Accuracy
  3. Ease of implementation
  4. Cost of running

Nick_Pyner:
Not really, as I only use bluetooth and internet myself, but your options are a lot wider than just WiFi or bluetooth. For starters, you might consider the NRF24 transceivers. They can be used in a network and have extremely low power consumption. Another is the XBee system.
FWIW I think it should be possible to use bluetooth for this but I'm not sure anybody else does. It it can be done it would probably be by having one Arduino poll the other and then send data from both to the PC.

For hardware, I can only suggest the DS18B20 temperature sensor and Arduino Unos as obvious choices, they are cheap, easy to use, and well-supported on this forum.

Your battery requirement is likely to depend as much on software, duty cycles etc. as much as hardware, and would probably be a case of suck it 'n' see.

i just needed raw data transfer into PC . if i use heartbeat rate sensor using bluetooth, is there any small batteries that supports 7-8 hours?

Grumpy_Mike:
What sort of accuracy and range are we talking about for the temperature measurements?

Just a reminder that there is no perfect solution to anything, the whole of engineering is a compromise, You have to specify things a lot more closely to allow good calls to be made on the compromises you need to make.
Some conflicting requirements could be

  1. Cost system
  2. Accuracy
  3. Ease of implementation
  4. Cost of running

every 45 seconds temperature value data must transfer into PC. and every changing moment accelerometer value data must transfer into PC. i worried about power consumption and size of the battery.

What is a "changing moment"? Do you mean that every time the accelerometer detects a change, data gets sent?

Can you save it up and send in a burst? How often is a "moment"?

BTW, please try not to write your replies inside the quoted text. Makes it difficult to pick out what you are saying.

oneup:
is there any small batteries that supports 7-8 hours?

I'm not a battery expert but a Uno draws about 45mA and I guess you can double that for the sensors, so 100mA. This sounds like a situation for five or six NiMH AAs which are commonly 1500mA, and therefore should to deliver 100mA for 15 hours. I think it is reasonable to expect them to deliver reliably for half that time.

An Uno has a lot of stuff that draws current while not needed in a final circuit. In addition, linear regulators waste power, which is what is on the Uno.

There are methods to reduce power - send the Atmel to sleep with Wake on Interrupt, low power sensors, send the sensors to sleep when not taking readings, that sort of thing.

You have still not said anything about the accuracy or resoloution of the temprature readings. The output from an accelerometer has a lot of noise on it and so changes all the time. Even sampling at 2000 samples per second you could miss changes. That is a lot of data and you might have to rethink that bit, like doing an average on the signals before you send it. How often are you expecting the acceleration readings to change?