Texas Instruments TMCS112x Precision Hall-Effect Current Sensor Use Case

Example demonstrating real-time output uncertainty estimation for calibrated ADC values from the TMCS112x sensor¹.

Introduction

The TMCS1123 is a precision Hall-effect current sensor.

Getting started

The correct way to clone this repository to get the submodules is:

	git clone --recursive [email protected]:signaloid/Signaloid-Demo-Sensors-TexasInstrumentsTMCS112xConversionRoutines.git

If you forgot to clone with --recursive and end up with empty submodule directories, you can remedy this with:

	git submodule update --init

Running the application locally

Apart from using Signaloid's Cloud Compute Platform, you can compile and run this application locally. Local execution is essentially a native Monte Carlo implementation, that uses GNU Scientific Library (GSL)² to generate samples for the different input distributions. In this mode the application stores the generated output samples, in a file called data.out. The first line of data.out contains the execution time of the Monte Carlo implementation in microseconds (μs), and each next line contains a floating-point value corresponding to an output sample value.

In order to compile and run this application in the native Monte Carlo mode:

0. Install dependencies (e.g., on Linux):

sudo apt-get install libgsl-dev libgslcblas0

1. Compile natively (e.g., on Linux):

cd src/
gcc -I. -I/opt/local/include main.c utilities.c common.c uxhw.c -L/opt/local/lib -o native-exe -lgsl -lgslcblas -lm

2. Run the application in the MonteCarlo mode, using (-M) command-line option:

./native-exe -M 10000

The above program runs 10000 Monte Carlo iterations. 3. See the output samples generated by the local Monte Carlo execution:

cat data.out

Inputs

The inputs to the TMCS1123x3A sensor conversion algorithms are the analog output voltage of the sensor ($V_{\mathrm{out}}$) as well as the zero current reference output voltage ($V_{\mathrm{ref}}$). The algorithm models the ADC quantization error as well as the uncertainty in the supply voltage using uniform distributions.

The uncertainty in $V_{\mathrm{out}}$ is modeled as a (UniformDist(3.2, 3.4)) Volts.

The uncertainty in $V_{\mathrm{ref}}$ is modeled as a (UniformDist(2.4, 2.6)) Volts.

Outputs

The output is the calibrated electric current (in Ampere):

$$\mathrm{Calibrated Sensor Output} = \frac{V_{\mathrm{out}} - V_{\mathrm{ref}}}{S}$$

where S is the sensitivity of the specific device and is modeled as a constant:

$$\mathrm{S} = 0.075$$

Following is an example output, using Signaloid's C0Pro-S core.

Usage

Example: TMCS1123x3A sensor conversion routines - Signaloid version

Usage: Valid command-line arguments are:
	[-o, --output <Path to output CSV file : str>] (Specify the output file.)
	[-S, --select-output <output : int>] (Compute 0-indexed output, by default 0.)
	[-M, --multiple-executions <Number of executions : int (Default: 1)>] (Repeated execute kernel for benchmarking.)
	[-T, --time] (Timing mode: Times and prints the timing of the kernel execution.)
	[-b, --benchmarking] (Benchmarking mode: Generate outputs in format for benchmarking.)
	[-j, --json] (Print output in JSON format.)
	[-h, --help] (Display this help message.)

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Footnotes

1. TMCS1123 Precision 250kHz Hall-Effect Current Sensor With ±1.3kV Reinforced Isolation Working Voltage, Overcurrent Detection and Ambient Field Rejection. ↩

2. GNU Scientific Library. ↩