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pressure sensor to microcontroller

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anju420

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i have an adp5100 pressure sensor with output voltage range of 0.45-4.5V (100kPa)
questions:
1. is there any equation to convert pressure to voltage?
2. how do i interface this to an MSP430 microcontroller?
will using a voltage follower circuit followed by a 16bit ADC do the job?
any suggestions as to what ICs to use/circuits?
 

I couldn't find a datasheet for your device.
If the output impedance of the sensor is high then you can use an opamp as unity gain amplifier (buffer) so that the A/D works properly.
If your A/D range can't work up to 4.5v then you have to add a voltage divider in the buffer output to lower the voltage before feeding the A/D input.

Alex
 

i have attached the datasheet of the sensor...
assume i'm simulating the output of the sensor...lets say my circuit will be as follows:
i give a 0-4.5V signal to an opamp (OA365) which is connected as a unity gain amp...the output of the opamp to the +IN of ADS8326 which is inturn connected to the MSP.
will this do? any other alternatives for the ICs I have chosen as the ones i opted for are expensive?

also, what abt my first query...how do i convert pressure in kPa to voltage for this sensor?

my application is for blood pressure monitoring.
 

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I have never used a pressure sensor but the datasheet has a graph on page

ADP5100.jpeg

According to the graph the pressure is
0.5v for -100kPa
4.5v for 100kPa

so 2.5v is 0,
you can use (Vmeasured-2.5)*50(kPa) so
when measured voltage is 0.5 it gives 0.5-2.5=-2*50=-100kPa
when measured voltage is 2.5 it gives 2.5-2.5=-0*50=-0kPa
when measured voltage is 4.5 it gives 4.5-2.5=2*50=100kPa

You can use an external A/D of the one on your mcu, it depends on the accuracy you want.

Alex
 
my sensor output impedance is 50ohms...like i said before, i need to simulate this signal...so i thought i would use a function generator to give a signal varying from 1 to 10kHz with amplitude varying from 0.45 to 4.5 V...can i give this signal directly to the internal opamp of the msp430 which acts a voltage follower and then configure the opamp to give its output to the internal adc12 of the msp430
 

hi , are u doin blood pressure project? if yes can u share with me, wat item require and ur circuit design .. THX! or u may email to me.(register.account@hotmail.com)

any of ur help is much appreciated!


currently im designing a blood pressure hardware, with the use of PIC, and display via PC


Everybody is welcome to leave me some comments.
Thanks!:grin::grin:
 

Use LM30 op amp which is linear and accurate .as interface between pressure sensor and ADC .The offset can be provided to this for 0.45vdc annuling to zero.
 

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