ChocoBox

Environment replicator for cocoa fermentation:

• Electronic system that replicates a real life environment. Includes:
  • Continous environmental humidity and temperature measurement
  • Real-time control of both humidity and temperature
  • Spline generation to emulate environmental changes
  • Intuitive set-up and data collection via .txt files
• Backend developed using the Arduino Framework and an ESP32 development board.
• Frontend mobile app developed using the Expo Framework and React-Native.
• Developed in the Universidad de Los Andes for the Biomicrosystems research group.

Developed by:

• Juan Sebastián Ortega (https://github.com/tadzio8425)
• Nicolás Correal (https://github.com/Correaln47)

Quickstart

1. Setting-up the files...

i. Creating the files

The ChocoBox system uses three .txt files inside a MicroSD Card in order to function, these files are environment.txt, spline.txt and datalog.txt. Altough these files have the .txt format, their content is designed to be read as a .csv. For the proper functioning of the system, it is obligatory for the files to be named exactly like this. If it is your first time using ChocoBox, or if you are resetting the system, please delete all previous files from the SD Card and create three empty .txt files.

a. Contents of the MicroSD Card

ii. Setting-up the environment

The environment to be replicated can be easily set in the environment.txt file. In order to to this, simply write the csv headers in the first row. These headers should be hour, temperature, humidity. Then, following the header order, write the desired values for specific hours in each new line. For example, this file replicates an environment for 96 hours, setting new desired values each 24 hours. There is no inverval restriction, neither there is a necessity for an interval, just make sure that the next hour is always greater than the previous one! Please make sure that there are no extra new lines or blank spaces!

b. Example of an environment.txt file

iii. Joining the dots

In order to replicate how these variables behave smoothly in nature, a cubic spline algorithm is used in order to fill the gaps between the dots set in environment.txt. The results of this algorithm are saved by the microcontroller in spline.txt, so this file must not be modified in any way by the user. If the reference values shown by the system are not logical, please check the spline.txt file. A spline.txt with Nan values or other errors indicates that environment.txt was wrongly formated!

c. Example of a correctly generated spline.txt file

iv. Step by step

A fundamental part of the spline algorithm is the step, this value determines the interval for intermediate points to be calculated and also for data capture. For example, a step of 30 minutes will make the system update its reference values and save its environmental data each, well, 30 minutes. The smaller the step, the more data will be captured and the smoother the system will be. Beware of using extremely small steps, as they may lead to a memory overflow in the ESP32! The step can be modified by the user, this will be explained in a further section.

v. Getting the data

All environmental data captured by the sensors is saved in datalog.txt, which is automatically updated by the microcontroller. This file includes the sensed information of each individual humidity and temperature sensor, captured each step. This file follows the order of the following headers: time(min), tempA(degC), tempB(degC), tempC(degC), tempD(degC), humidLeft(%), humidRight(%)

The presence of Nan values in this file may indicate a sensor malfunction!

d. Example of a correctly generated datalog.txt file

2. PCB Connections

Handling the PCB should be avoided at all costs. However, in the case that something has gone wrong or a new interface/sensor needs to be added, the following connection diagram should be strictly followed. All cables are marked with their respective signal.

3. Cable management

ChocoBox uses an electric extension to power itself, the extension input should be conected directly to the power socket. This extesion has 3 available output sockets, of which only 2 are actually used. One of the sockets must me connected to the resistor cable, which handles the power given to the heating resistors. The second socket must be connected to a 12V-2A power supply that powers the electronics. The output of the power supply is a jack connector which goes directly into the PCB box. Remember that you may find the extension sockets on the floor, behind the resistor wooden holder. Please make sure that all major cables are correctly pluged-in before performing any test, also do not handle cables under any circumstance unless the resistors are totally cold.

• To completely TURN-OFF the system, you only need to unplug the extension input from the power socket.

4. Operating the system

Once everything is pluged-in, the system should start to work autonomously. This means that the desired values from environment.txt will be replicated inside the box, following the intermidiate points generated in spline.txt and the actual sensed values will be saved each step in datalog.txt.

i. Monitoring 01: LCD Screen

The most straigth-forward method to monitor the system is by looking at its 20x4 LCD Screen. This screen depicts the following data, line by line:

1. Humidity: Displays the current humidity average inside the box in (%).
2. Temperature: Displays the current temperature average inside the box in (°C).
3. Ref: Displays the reference values that the system should be trying to achieve in that specific moment.
4. Time: Displays how much time has the system been on a specific fermentation cycle. This timer DOES NOT reset when the system is disconnected, as it is programmed to retake fermentation despite a possible temporal failure. However, it can be reset manually.

ii. Connecting to the ESP32 via WiFi

The ESP32 is set in AP mode, which means that it acts as an Access Point (A.K.A. its own WiFi network). In order to connect, simply search for the network called ChocoBox and establish a connection using the secret password. It is important that this password is only given to authorized staff, otherwise, a fermentation cycle could be jeopardized.

• Once connected to the ChocoBox network, the ESP32 can be accessed using its IP Address which will always be:
• 192.168.1.1

iii. Monitoring 02: Rest API

Accessing the root of the rest API via any browser (192.168.1.1/) displays the current state of its variables. Thus, ChocoBox can be monitored in real time without the need of an external app.

iv. Monitoring 03: App

An app was developed using the Expo Framework in order to unify all the API Requests in an intuitive and user friendly interface.