Circuit for NPP-301A 100PSI IC (Pressure sensor) combined with MAX1472AKA+T

Thread Starter

NairVI

Joined Feb 16, 2019
14
Hello all,

Can someone please help me out for building a basic circuit for getting these sensors to give readings. The sensor I'm using is NPP-301A 100PSI IC (Pressure sensor) combined with MAX1472AKA+T RF TRANSMITTER..... I'm a software engineering student.. and I have very little knowledge over basic electronic components and circuit building. The help I need is, what and all components needed to complete the circuit. I will be using 3V Li battery (CR 2032) for the circuit. The reading will happen in Arduino side with a basic RF receiver. Can u or anyone plz help me to plot a circuit for the same.

The inspiration for the project was from the below link if that will help you all for understanding better:
https://hackaday.io/project/7077-no-battery-nfc-air-pressure-sensor

And my idea is to live tract the pressure.

Please find attachments for the datasheet of the above-used sensor and RF Transmitter.


Guide me if possible

Thanks a lot in advance
 

Attachments

Thread Starter

NairVI

Joined Feb 16, 2019
14
hi Nair,
Welcome to AAC.
For the pressure sensor a Instrumentation Amplifier [IA] would be one option.
Amplify the 0mV thru 30mV pressure signal to say 0V thru 2.5V.

E
Thanks a lot, ericgibbs,
And sorry for disturbing you yet more, but can you specify the pin diagram for the pressure sensor and rf transmitter to connect. As I said I'm a noob in electronics on this level.
Thanks a lot in advance.
 

Thread Starter

NairVI

Joined Feb 16, 2019
14
hi,
This image shows the pin numbers for the sensor.
Note: the 100R trim pot option can be used to zero the sensor bridge output.

The gain adjust post would be a 2K trim pot.

E
Thanks a ton, ericgibbs.
I will soon get into work with this. Yet I have few doubts on how to get the signal and pass it through the rf transmitter and all. But let me try first and let you know the result.
 

Thread Starter

NairVI

Joined Feb 16, 2019
14
hi Nair,
Do you plan to digitise the Vout of the AD623, say using a MCU with a inbuilt ADC.?
E
Yes, Raspberry Pi has analog pins where I can get reading from
I am gonna use "Raspberry PI GPIO" pins to read the values initially.. later an RF transmitter (MAX1472AKA+T) to relay the data so that I can receive through a random RF receiver. Do you think its the right idea??
 
Last edited:

ericgibbs

Joined Jan 29, 2010
12,269
hi,
An alternative to AD623, could be a HX711 module.
It is designed to power and read a bridge, its output is a pulse train, Arduino code exists for this device.
Look thru this HX711 PDF, it may be an easier option.
E

Added PCB:
AD amp.png
 

Attachments

Last edited:

Thread Starter

NairVI

Joined Feb 16, 2019
14
hi,
An alternative to AD623, could be a HX711 module.
It is designed to power and read a bridge, its output is a pulse train, Arduino code exists for this device.
Look thru this HX711 PDF, it may be an easier option.
E
Thanks again brother,

But I am going to put it inside a running live tyre. so to reduce the drag and weight I have opted this specific IC's. But as you know now my limited knowledge is jeopardizing the whole project. So far I need a circuit so that I can give power(3V Li batter[big button cell]) to NPP-301A pressure sensor and get the output across RF Transmitter (MAX1472AKA+T)

Once this is done I can receive the signal from an ordinary RF receiver which is connected to either Raspberry PI or Arduino.

Please tell me if im doing anything wrong.
 

Thread Starter

NairVI

Joined Feb 16, 2019
14
hi Nair,
Do you plan to digitise the Vout of the AD623, say using a MCU with a inbuilt ADC.?
E
Sorry .. I did my research and raspberry pi doesn't have ADC, but however, my question is cant I just send the data to an RF transmitter as I'm using with MAX1472. please review the circuit diagram I'm uploading too and suggest me how to connect the ad623 output to max1472 data input. Consider me as a noob in circuits and please explain to me how can I get crystal oscillator to perform in 9.8MHz as specified in the diagram.
Thanks a ton in advance.
 

Attachments

ericgibbs

Joined Jan 29, 2010
12,269
hi Nair,
You can add that trim pot in the 0V wires of the two bridge arms, it makes it possible to trim out any imbalance in the bridge output.
E

AA1 16-Feb-19 13.27.jpg
 

ericgibbs

Joined Jan 29, 2010
12,269
hi Nair,
Please post a diagram showing which modules you are now using and how they are connected.
If you are using a HX711 module, to which micro-controller is it connected.
With this information it should be possible to work out a method of transmitting the data, again we must know which modules you have the receiving end of the project.
E
 

Thread Starter

NairVI

Joined Feb 16, 2019
14
Hi Sir,
These are the list of modules i'm using,
1) NPP301a (Pressure sensor 100PSI)
2) AD623ARMZ (surface mounted)

Trying as per to this diagram you posted a while ago sir, Using all surface mounts



3) MAX1472 AKA+T (RF Transmitter)
4)Raspberry Pi on the receiving end

Connections needed:
1) NPP301A connected to MAX1472 in a separate etched PCB with a 3v cr2032 button cell. This whole assembly will be placed inside the tyre.
2) Raspberry PI connected to the RF receiver, which receives the data transmitted from above said PCB which is placed inside the Tyre.

Please refer the hand-drawn image to get a bit of an idea. And I am extremely sorry to as so much of dumb questions, this is my first step towards Embedded from software

Please find the attachments and reply me back does it give you enough input for the process

Thanks a lot in advance

1.jpg

2.jpg
 
Last edited:

ericgibbs

Joined Jan 29, 2010
12,269
hi,
The output from the NNP301 is approx 30mV maximum with a 3V supply. I would say that that mV DC signal needs to amplified and encoded prior to transmission.
What method have you considered in encoding that signal before transmission.?
I did show a method using a HX711 and a MCU, that would output a serial data string that could transmitted.
You said that method was suitable, as you wanted to keep the module inside the tyre as small as possible.
E
 

Thread Starter

NairVI

Joined Feb 16, 2019
14
sure, will definitely start on that work. and in your free time please give me inputs on MAX1472 as well. datasheets as already been uploaded in the previous post.
Once again thanks a lot for your effort, sir.
 
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