Good evening all,
Background: I am final year Electrical & Electronic engineering student currently in the process of completing my undergraduate thesis. The thesis topic consists of making a low-cost, non-intrusive, battery powered electronic device that is small enough to fit in the punt (the under dome) of a wine bottle. This electronic device will be used to track the storage conditions (temperature, humidity, and ambient light) of luxury wine. A user-interface will be used to display the storage conditions. The aim of this device is to give confidence to the buyer that a wine has not been spoilt when bought at auction, wine retailers ect. I am currently busy with the hardware design, and I’ve hit a roadblock. I feel as if I’m heading in the total wrong direction. Any guidance/advice will be appreciated. I have chosen to use the DF robot beetle (https://www.dfrobot.com/product-1075.html) as the micro-controlling unit (MCU). The 5V MCU will act as the master and communicate with sensors (which will act as slaves) via I2C. The sensors which I’ve chosen are:
• Contactless infrared temperature sensor - https://neotronics.co.za/index.php?route=product/product&product_id=608 which will act as the main temperature sensor and will be pointed upwards through the bottle from 3D printed housing.
• BH1750FVI digital ambient light sensor - https://www.elechouse.com/elechouse/images/product/Digital%20light%20Sensor/bh1750fvi-e.pdf
• SHT3x-DIS Humidity and temperature sensor - https://docs.rs-online.com/c777/0900766b816bf6ab.pdf the second temperature sensor will act as a backup and ensure the main sensor is operating correctly.
The problem comes in with the battery. The device will be taking reading once every hour and then deep sleep will be activated. The goal is to use a primary battery (non-rechargeable) and attempt to get 1-3 years of operation time. I originally wanted to use coin-cells battery’s due to the low profile, but they are only useful in low current projects. I have settled on a 9V lithium battery which has a rather large profile (https://docs.rs-online.com/fabf/0900766b81549eff.pdf). The 9V battery will be connected to a switching 5V regulator (thanks to the comments) to power the microcontroller. An LDO will then be used to step down the 5V rail to 3.3V for the sensors. A PCB will be designed using Altium and housing with Autodesk inventor. UART will be used to communicate to the user-interface, or a removable SD card will be implemented on the PCB if there is enough space.
The questions I have are:
- The battery solution is inefficient, I know that there are better approaches to solve this solution. What are the advantages of using an Arduino Nano (a much larger board) which has an input voltage of 7-12V and offers both 5V and 3.3V pins? In what areas is this solution be better than using the beetle?
- How can I go about calculating the total power dissipation (deep sleep/ then active I2S communication) of the system? Will phyiscal testing be a more appropriate approach? I would like to use this calculation to estimate the potential battery life.
- Are there any other microcontrollers that may be more appropriate for this context? An intrusive design is on the cards but the objective for now is to keep the design non-intrusive.
Any help/suggestions will be greatly appreciated :) Sorry for the long read!