Documentation sections

Pressure Sensor Bridge Output

POSThttps://rftools.io/api/py/v1/calculate

Slug pressure-bridge-output. Calculate bridge output voltage for piezoresistive pressure sensors. Determine mV output from excitation voltage, sensitivity, and applied pressure.

Inputs

Send every one of these in inputs, in the units shown. Most are required: a call without one is refused (400) and costs nothing; one the calculator can do without takes the default shown. An input outside its range is still computed and flagged in the provenance.

Inputs of pressure-bridge-output
Name	Unit	Range	Default	Description
excitationVoltagenumber	V	at least 0.1	5	Bridge Excitation Voltage
bridgeSensitivitynumber	mV/V	at least 0.001	10	Full-scale output in mV per V of excitation
appliedPressurenumber	kPa	at least 0	50	Applied Pressure
fullScalePressurenumber	kPa	at least 0.001	100	Full-Scale Pressure
frontGainnumber	V/V	0.01 … 100000	60	The gain between the bridge output and the ADC. A gain of 60 brings a 50 mV full-scale output to 3 V.
adcRefnumber	V	0.1 … 50	3.3	The ADC full scale
adcBitsnumber	bit	1 … 24	12	ADC resolution in bits

Outputs

Returned in values, by key. A value that is unbounded or undefined is null.

Outputs of pressure-bridge-output
Field	Unit	Description
bridgeOutputMvheadline	mV	Bridge Output
fullScaleOutput	mV	Full-Scale Output
fractionalDeflection	%	Fractional Deflection
amplifiedVoltage	V	The bridge output times the amplifier gain
adcCode	none	The code an ideal ADC reads: floor(V_amp / V_ref × 2^N)
resolution	kPa/LSB	The pressure one ADC step spans

Calling it

Calculate: one call, the request and response in full, and its errors.
Batch: this calculator with others, or a sweep, in one request.
Solve for a target: the value of one input that brings an output to a target.

curl -X POST https://rftools.io/api/py/v1/calculate \
  -H "X-API-Key: $RFTOOLS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "slug": "pressure-bridge-output",
    "inputs": {
      "excitationVoltage": 5,
      "bridgeSensitivity": 10,
      "appliedPressure": 50,
      "fullScalePressure": 100,
      "frontGain": 60,
      "adcRef": 3.3,
      "adcBits": 12
    }
  }'

import rftools

client = rftools.Client()  # reads RFTOOLS_API_KEY, or the key `rftools login` saved

result = client.calculate("pressure-bridge-output", {
    "excitationVoltage": 5,
    "bridgeSensitivity": 10,
    "appliedPressure": 50,
    "fullScalePressure": 100,
    "frontGain": 60,
    "adcRef": 3.3,
    "adcBits": 12,
})
print(result.values)
print(result.warnings, result.provenance.formula_ref)

const response = await fetch("https://rftools.io/api/py/v1/calculate", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.RFTOOLS_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "slug": "pressure-bridge-output",
    "inputs": {
      "excitationVoltage": 5,
      "bridgeSensitivity": 10,
      "appliedPressure": 50,
      "fullScalePressure": 100,
      "frontGain": 60,
      "adcRef": 3.3,
      "adcBits": 12
    }
  }),
});
console.log(response.status, await response.json());

package main

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	body := []byte(`{
	  "slug": "pressure-bridge-output",
	  "inputs": {
	    "excitationVoltage": 5,
	    "bridgeSensitivity": 10,
	    "appliedPressure": 50,
	    "fullScalePressure": 100,
	    "frontGain": 60,
	    "adcRef": 3.3,
	    "adcBits": 12
	  }
	}`)
	req, err := http.NewRequest("POST", "https://rftools.io/api/py/v1/calculate", bytes.NewReader(body))
	if err != nil {
		panic(err)
	}
	req.Header.Set("X-API-Key", os.Getenv("RFTOOLS_API_KEY"))
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	out, _ := io.ReadAll(res.Body)
	fmt.Println(res.Status, string(out))
}

application/json

{
  "slug": "pressure-bridge-output",
  "values": {
    "bridgeOutputMv": 25,
    "fullScaleOutput": 50,
    "fractionalDeflection": 50,
    "amplifiedVoltage": 1.5,
    "adcCode": 1861,
    "resolution": 0.02685546875
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:pressure-bridge-output",
    "version": "api@3f2c1a9b04de",
    "formulaRef": null,
    "assumptions": [],
    "validRange": {
      "status": "inside",
      "bounds": {
        "excitationVoltage": {
          "min": 0.1,
          "max": null,
          "unit": "V"
        },
        "bridgeSensitivity": {
          "min": 0.001,
          "max": null,
          "unit": "mV/V"
        },
        "appliedPressure": {
          "min": 0,
          "max": null,
          "unit": "kPa"
        },
        "fullScalePressure": {
          "min": 0.001,
          "max": null,
          "unit": "kPa"
        },
        "frontGain": {
          "min": 0.01,
          "max": 100000,
          "unit": "V/V"
        },
        "adcRef": {
          "min": 0.1,
          "max": 50,
          "unit": "V"
        },
        "adcBits": {
          "min": 1,
          "max": 24,
          "unit": "bit"
        }
      },
      "outside": [],
      "model": null
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "excitationVoltage": 5,
      "bridgeSensitivity": 10,
      "appliedPressure": 50,
      "fullScalePressure": 100,
      "frontGain": 60,
      "adcRef": 3.3,
      "adcBits": 12
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "excitationVoltage"
      ],
      "msg": "Input should be a valid number, unable to parse string as a number",
      "input": "abc"
    }
  ]
}

An input sent as text. Nothing was counted.

{
  "detail": "More than 120 requests in 60 seconds from this address.",
  "errorKind": "rate_limited",
  "limit": 120,
  "windowSeconds": 60,
  "upgradeUrl": "https://rftools.io/pricing/"
}

Too many requests in a minute, with Retry-After.

Same inputs on the calculator pagePressure Sensor Bridge Output, at these values