BFG Research

HIL Branch Configuration

Overview

This branch is specifically set up for Pradeep Kumar's HIL Temperature Project.

This project uses the following devices:

INA260
LC709203F
MAX31855

This configuration does NOT use the TCA9548A multiplexer. There are no address conflicts between the devices, and the TCA9548A is not necessary. That said, both I2C devices (INA260 and LC709203F) will be connected to the same I2C bus in parallel.

Running the Program

Once arduino.ino has been programmed to the Arduino, connect over USB. In src/Devices.py, on Line 8, set the serial port to whichever port the Arduino is on.

Request frequency is set using the Hz variable set at the top of src/main.py.

Run src/main.py with python3, and the program will run, collecting data from the devices.

Collected data, as well as a log, is stored in data/, in .csv and .txt files.

Summary

This repository is for development of data collection programs for a Raspberry Pi Zero, testing and comparing different Battery Fuel Gauges.

To install dependencies, please run: pip install -r src/requirements.txt

To run the program, please run: python src/main.py

The arduino-cli project is used for compiling and uploading the Arduino code on a command line, using the Makefile. Do steps up to and including Adding to $PATH, and then use make libraries in the arduino folder to install the avr binary and the arduino libraries.

Devices Interfaced

Product Page	Datasheet	Arduino Library	Manufacture	Description
LC709203F	Short Guide	Adafruit_LC709203F	AdaFruit	BFG, reads a combination of voltage and current, to estimate the battery's charge and capacity.
LTC2941	Datasheet	Seeed_LTC2941	Analog Devices	BFG, Measures mAh drawn from a LiPo battery.
MAX17043	Datasheet	SparkFun library	Analog Devices	BFG, Measures mV across battery cell for estimate.
TCA9548A	Datasheet	GitHub	AdaFruit	An I2C multiplexer, for connecting all devices to the arduino I2C bus.
SHTC3	Datasheet	GitHub library	AdaFruit	Adafruit Sensirion SHTC3 Temperature & Humidity Sensor
MAX31855	Datasheet	Arduino Guide, GitHub	AdaFruit	Thermocouple Amplifier MAX31855 breakout board, USES SOFTSERIAL. Uses pins 4,5,6
INA260	Datasheet	GitHub library	AdaFruit	Adafruit INA260 Current + Voltage + Power Sensor
INA219	Datasheet	GitHub library	AdaFruit	Adafruit INA219 Current Sensor

Implementation

Since two of the units are designed for Arduino, the simplest way to implement this is to use an Arduino, and get all data from the arduino, onto the pi, over serial.

The pi sends JSON payloads to the arduino, which unpacks them, grabs the necessary data from the device requested, repacks it, and sends it back to the pi.

The Python code for Pi is under src; the arduino code is under arduino

The Pi

The raspberry pi will be used for data collection, from the raspberry pi. The serial interface between the pi and the arduino will send requests back and forth. The easiest way to do this is with string requests.

The Arduino

The arduino will interface with all hardware devices over I2C. Whenever a request comes in for an update on a device from the Pi, the Arduino will read data on the appropriate I2C interface, and return the data as JSON payload.

Requirements

Data will be communicated over serial, in JSON format. Arduino library is ArduinoJSON.
Manage the I2C bus, using a multiplexer, to get data from the correct devices
All required key responses will be defined in a generic class, which will be a superclass to the BFG devices. This will allow for mosular queries.
The BFGs will be kept in a map, where keys are the device string names, and the values are the BFG objects. Each data key will be associated with a BFG function call, so the JSON string queries can be directly mapped to the BFG functions.

Table of Keys

Key	Description
D	specifies the device being queued
V	Battery Voltage (V)
I	Battery Current (mA)
W	Battery Wattage (mW)
C	Battery Capacity (mAh)
P	Battery Percentage (0-100)
T	Battery Temperature (C)
H	Ambient Humidity (Relative, %)

Table of Devices and Callable Attributes

Device	Update String	Description
SHTC3	TH	Temp, Humidity
INA219	I	Current sensor across shunt
MAX31855	TC	T thermocouple, C internal temp
MAX17043	VP	Voltage, Percentage on BFG
LC709203F	VPT	Voltage, Percentage on BFG, Temp on thermocouple
INA260	VIW	Voltage, Current, Power

*It should be noted that the MAX31855 can call T() for thermocouple reading, or C() for internal temp reading. C() usually returns capacity in mAh.

Device Communication

Device	Address
TCA9548A	0x70
LC709203F	0x0B
SHTC3	0x70
MAX31855	SPI
MAX17043	0x36
INA219	0x40
LTC2941	0x64
INA260	0x40

NOTE: The TCA9548 Multiplexer address needs to be changed to 0x71. This is done by pulling pin A0 HIGH.

Request JSON (Pi -> Arduino)

JSON requests will be one key/value pair. The key will be the device being queried, and the value will be an array of strings associated with values requested.

Response JSON (Arduino -> Pi)

Output JSON will be will be a dict of dictionary of key/value pairs. Each root query key is the device, to identify the device being echoed. The value data being sent will be the key/value pairs for queried data, for each key/device.

LOGGING/MESSAGE PACKETS

Payloads sent from the Arduino to the Pi can be marked as 'logging messages', which will be displayed to the terminal. This is useful for debugging, and for getting a sense of what is going on.

Messages are JSON payloads formatted as: {"D":"LOG","M":"<msg>"}.

Messages can be sent on the Arduino by calling the LOG(String msg) function.

colefuerth/BFG-Research