Cellular Temp-Humidity Sensor Design

@AwaisChaudhry

Hello, I will deliver a complete hardware-to-firmware solution for a low-power, standalone temperature and humidity monitor using a 4G/LTE path with ESP32 driving a SIM7600G module and a DHT22 sensor. The design will sleep most of the time, wake on schedule, take readings, publish securely via MQTT to your Supabase/PostgreSQL back-end, and then return to deep sleep. I will build robust reconnection logic for cellular loss and log failures for review, plus a battery-management stage to maximize efficiency from a Li-Po pack with USB-C charging and protection. The deliverables will include a clean, production-ready schematic (PDF + source), Gerber PCB files, and a well-documented Arduino/C++ firmware featuring adjustable wake intervals, reliable MQTT routines, resilient SIM7600G handling, and battery health reporting. I will also propose layout optimizations to improve efficiency and reliability based on the chosen parts and board constraints. Here are the important questions I would like you to answer to tailor the solution: What is the minimum required MTBF for the cellular link and what logging granularity do you prefer for failures? What back-end security method do you require for MQTT (TLS version, certificate pinning, client auth)? Do you have a preferred SIM or carrier profile for the 4G plan (APN, roaming constraints, data cap)? What wake interval range is acceptable (e.g., 5, 15, 30 minutes) and how should it be adjusted (serial commands or OTA)? What are the exa

@ITECH

With over a decade of experience in IoT, automotive electronics, and embedded systems, I am well-versed in tackling complex projects like your Cellular Temp-Humidity Sensor. My knowledge of Arduino, C++ Programming, and Microcontroller is a perfect match for your firmware needs. Additionally, my expertise in Electronics and PCB Design will ensure that the hardware aspect of your project is executed flawlessly. Efficiency, reliability, and maintainability are core principles I adhere to in every project. I aim to optimize power consumption while ensuring seamless functioning and continuous data logging. Rest assured; I will meticulously design and implement a battery management system that meets your requirements and delivers a minimalistic current draw of under 200 µA during sleep mode. Moreover, as a full-service product development team, we have a comprehensive understanding of software-hardware synchronization. Consequently, we can guarantee you a production-ready PCB layout with Gerber files along with a complete understandable schematic which will greatly simplify future maintanence. Finally , my proficiency in MQTT routine targeting Supabase/PostgreSQL ensures safe and secure data transfer to your preferred database. Let's collaborate to bring your vision of a low-power temperature and humidity monitor into reality!

@macroenergy

As someone with extensive experience in Arduino and C/C++ Programming, I bring a wide range of relevant skills to your Cellular Temp-Humidity Sensor Design project. My deep understanding of Electronics and Embedded Systems combined with my proficiency in Microcontroller programming make me the ideal candidate for the job. I have been designing hardware systems across industries for several years, including those with low-power functioning like yours. Moreover, my strength in PCB Design and Layout is critical for delivering a robust solution that caters to your specific needs. I will provide you with a complete, readable schematic and a production-ready PCB layout which exceeds your expectations. Additionally, my familiarity with MQTT as well as successful integration of SIM7600G in various designs now help me assure that not only will my firmware ensure secure publishing of readings over MQTT to your desired Supabase/PostgreSQL backend but also take care of lost cellular links by attempting graceful reconnection. My promise is not only to meet but exceed your expectations through uninterrupted MQTT posting, efficient deep-sleep logic ensuring battery life and capturing potential issues in our logs.

@engrusmanfaiz

Dear Sir, I can develop the complete low-power LTE temperature/humidity monitoring system from hardware through firmware. I have experience with ESP32, SIM7600-series LTE modules, MQTT systems, and battery-optimized IoT devices. The design will be optimized for ultra-low standby current and reliable long-duration field operation. I will implement efficient deep-sleep management, watchdog/reconnection logic, and robust MQTT publishing. Special attention will be given to SIM7600G power stability since LTE current spikes can cause brownout issues. The PCB will include Li-Po charging, USB-C power input, battery protection, and accurate battery monitoring. Firmware will support adjustable wake intervals, logging, fault recovery, and clean serial configuration. Deliverables include schematic, PCB, Gerbers, BOM, and fully documented Arduino/C++ firmware. I will also optimize layout and regulator selection to help achieve the <200 µA sleep-current target. Ready to begin immediately after confirming enclosure size and deployment conditions.

@polto

hi I have the experience to do this project and the equipment too. to make a prototype in my place then I can make the pcb using kicad to direct printed in pcbway I prefer a fixed price 600$ for this project I can make the prototype for free before accepting the bid

@tangramua

Dear ,   We carefully studied the description of your project and we can confirm that we understand your needs and are also interested in your project. Our team has the necessary resources to start your project as soon as possible and complete it in a very short time.   We are 25 years in this business and our technical specialists have strong experience in C Programming, Electronics, Microcontroller, C++ Programming, Arduino, MQTT, Embedded Systems, PCB Design and Layout and other technologies relevant to your project.   Please, review our profile https://www.freelancer.com/u/tangramua where you can find detailed information about our company, our portfolio, and the client's recent reviews.   Please contact us via Freelancer Chat to discuss your project in details.    Best regards, Sales department Tangram Canada Inc.     

@Adeel2k14

Hello, I am an Electrical Engineer with 6+ years of experience in embedded systems, firmware, and IoT product development. I have strong expertise with ESP32, Atmel, and PIC microcontrollers, along with SIMCOM modules and MQTT-based communication systems. I have worked on IoT platforms such as ThingsBoard, Blynk, and Arduino IoT Cloud, and I am experienced in Arduino IDE, MPLAB XC8, PlatformIO, HTML/CSS, MQTT, HTTP, and WebSockets. I can design the complete low-power hardware solution, develop reliable firmware with deep sleep and LTE reconnection handling, and deliver production-ready PCB files. I can also share previous related project samples for reference.

@majeed219

As an adept Embedded Systems Engineer and experienced Professional PCB Designer, I’m thrilled to offer my skills for your Cellular Temp-Humidity Sensor Design project. With your heavy reliance on ESP32 & SIM7600G functionality, paired with DHT22 sensor integration, my extensive work with similar setups can ensure a dependable and cost-effective design solution. I have designed automated lighting systems using STM32 that guarantee optimal power-efficiency solutiions just like those you require. Furthermore, my expertise with IoT Modelling including free data streaming with Adafruit IO, Arduino cloud and Thingsboard, along with a deep understanding of MQTT protocol targeting Supabase/PostgreSQL used for tracking various Industrial IoT projects means I can confidently provide the smooth back-end system you need. I’m not only capable of crafting comprehensive schematics (PDF/styles) and optimised PCB layouts with Gerber files but also arrived at the most efficient designs by highlighting the layout tweaks and component choices. Additionally, having dealt with numerous battery-powered devices projects, including Low-power PCBs with multiple sensor integration for wireless data transmission, I can ensure your device successfully runs on the Lipo pack in exceedingly low current needs below 200μA while uninterrupted MQTT posting, even with the weak or lost cellular link. Let’s bring your 'templytics' ideas to life with innovation, precision, and sleep-savvy!

@hayat38402

Hi, how are you doing? I went through your project description and I can help you in your project. your project requirements perfectly match my expertise. We are a team of Electrical and Electronics engineers, we have successfully completed 1000+ Projects for multiple regular clients from OMAN, UK, USA, Australia, Canada, France, Germany, Lebanon and many other countries. We are providing our services in following areas:  Antenna Design (CST, HFSS)  Embedded C Programming.  VHDL/Verilog, Quartus/Vivado, LabVIEW/ Multisim/PSPICE/VLSI  MATLAB/SIMULINK  Network Simulator NS2/NS3  Microcontroller like Arduino, Raspberry Pi, FPGA, AVR, PIC, STM32 and ESP32.  IDEs like Keil MDK V5, ATmel studio and MPLab XC8.  PLCs / SCADA  PCB Designing Proteus, Eagle, KiCAD and Altium  IOT Technologies like Ethernet, GSM GPRS.  HTTP Restful APIs connection for IOT Communications. Also, we have good command over report writing, I can show you many samples of our previous reports. Kindly consider us for your project and text me so that we can further discuss specifically about your project's main goals and requirements.

@hamzazayyad

Dear Sir, I am an Electronics Engineer with more than 15 years of exoeriance in the field, seeking a complete hardware-to-firmware solution for a low-power standalone temperature and humidity monitoring device using 4G/LTE communication. System requirements: • ESP32 as the main controller • SIM7600G LTE module for cellular connectivity • DHT22 temperature/humidity sensor • MQTT publishing to a Supabase/PostgreSQL backend • Battery-powered operation using a Li-Po pack • USB-C charging with protection and power-management circuitry Device operation: • System remains in deep sleep most of the time • Wakes on a scheduled interval • Reads sensor values • Publishes data securely over MQTT • Detects cellular connection loss and reconnects automatically • Logs communication failures for later diagnostics • Returns to deep sleep after transmission Please provide: • Complete schematic (PDF + editable source files) • Production-ready PCB layout and Gerber files • Fully documented Arduino/C++ firmware including: – Adjustable deep-sleep intervals via serial – MQTT communication with Supabase/PostgreSQL – Robust SIM7600G reconnection and error handling – Battery monitoring and health reporting • BOM with footprints and recommended components Performance targets: • Stable 24-hour battery-powered bench operation • Reliable MQTT posting every 15 minutes • Sleep current below 200 µA Best regards, Hamza Electronics Engineer

@mahmoudralizadeh

Hello, I went through your requirements carefully, and this is very close to the kind of remote telemetry hardware I’ve built several times around ESP32 + LTE architectures. The combination of ESP32, SIM7600G, MQTT telemetry, deep sleep management, and Li-ion battery operation is straightforward on paper, but getting it stable over long unattended operation is where most of the engineering effort actually goes especially with LTE power transients, modem recovery behavior, and achieving reliable low sleep current. I’ve worked on similar systems including: ESP32-based remote monitoring nodes LTE telemetry devices using SIM7600/SIM7000/A76xx modules Battery-powered environmental loggers MQTT reporting systems with offline buffering/retry logic Deep sleep optimization below sub-mA ranges USB-C powered Li-ion charging/protection designs Long-runtime field devices with watchdog and fault recovery handling For your target of <200 µA sleep current, the hardware partitioning and power tree will matter quite a bit. The SIM7600 itself can easily dominate leakage if the shutdown sequencing and rail isolation are not handled properly, so I’d likely separate always-on and switched domains carefully and evaluate whether the modem should be fully power-gated between wake cycles rather than left in modem sleep. On the PCB side, SIM7600 current spikes are usually the first place where otherwise “working” prototypes become unstable. I normally allocate substantial local bulk capacitance near VBAT, keep the high-current return path extremely short, and isolate RF and digital return currents properly. Placement around the antenna feed, matching region, and ground continuity also matters more than many expect with LTE modules. From the firmware side, I would structure the system as a small state-driven workflow rather than a linear loop: wake power validation sensor acquisition modem bring-up network registration MQTT session publish/acknowledge error handling / retry fault logging graceful shutdown deep sleep That makes recovery logic much cleaner when the modem partially hangs, registration stalls, or MQTT acknowledgements fail intermittently. For MQTT reliability, I’d avoid “fire and forget” publishing and instead implement explicit acknowledgement handling, bounded retries, modem reset escalation, and persistent failure counters. If cellular service is temporarily unavailable, readings can optionally be buffered locally and flushed on reconnection. For battery management, I’d likely use a dedicated Li-ion charger/protection approach rather than relying on simplistic USB charging circuits. USB-C sink configuration, charging thermal behavior, quiescent current, and battery protection thresholds all affect long-term reliability and standby current. The acceptance target of uninterrupted 15-minute reporting over 24 hours on battery is very reasonable provided the modem attach time is controlled properly and the network conditions are decent. The largest variable in power budgeting is usually LTE registration duration and signal quality. A few technical questions before defining the final architecture: 1. Which LTE bands and deployment regions are you targeting? That affects antenna selection, certification considerations, and sometimes modem variant choice. 2. Do you want the device to retain unsent measurements locally if the network is unavailable for several cycles, or is dropping missed samples acceptable? 3. Is OTA firmware update capability something you want designed in from the beginning, or should the system remain intentionally minimal? 4. Are you expecting TLS-secured MQTT connections to Supabase directly from the ESP32/SIM7600, or will there be an intermediate broker/server layer? 5. Do you already have a preferred charging IC or battery capacity target, or should I optimize the power stage around your runtime expectations? Deliverables would include clean schematics, production-ready PCB files, documented firmware, and test procedures/results for the power and telemetry validation. I also normally provide bring-up notes and debugging references so future maintenance is easier if the design evolves later. Communication-wise, I prefer short technical update cycles with incremental checkpoints rather than disappearing for a week and delivering everything at once. That tends to surface tradeoffs early, especially around power optimization versus reconnect latency. Happy to discuss architecture options as well particularly whether fully cold-booting the modem every cycle is preferable for your power target, or whether a faster reconnect strategy makes more sense for your deployment scenario.

@Feriver

This is a low-power IoT telemetry device project combining ESP32 + SIM7600G + DHT22 with deep sleep scheduling, LTE MQTT publishing, and battery-optimized PCB design for continuous environmental monitoring. I will design the complete hardware and firmware stack, starting with a power-optimized schematic that integrates ESP32 with SIM7600G using proper level shifting, power rail isolation, and LTE peak current handling. I will also design a Li-Po charging and protection circuit via USB-C with safe charging IC selection, ensuring stable operation during LTE transmission bursts. On the PCB side, I will deliver a production-ready layout with careful RF routing for the SIM7600G antenna, separation of analog/digital domains, and optimized trace design for low power leakage. The design will target ultra-low sleep current (<200 µA) through proper power gating of the modem and sensor subsystem. On firmware, I will implement deep-sleep scheduling with configurable wake intervals, robust LTE reconnection logic, MQTT publishing to your Supabase/PostgreSQL backend, and failure logging for connectivity issues. The system will include battery monitoring, health reporting, and graceful recovery when the cellular link drops. Firmware will be written in clean Arduino/C++ with modular structure for future expansion. Deliverables will include full schematics (PDF + source), Gerber files, BOM, and well-documented firmware ready for deployment and testing. Thanks, Asif

@Tmstudios

Hi, I'm really interested in working on this project! I have designed a similar board for a UAE client using the ESP32 and SIM7080G, communicating via AWS IoT Core.i can design you the same and deliver your hardware files (Schematic, PCB, and BOM) within 4 days and implement firmware for your backend. also can provide Support Assistance with JLCPCB ordering and assembly. if needed i can test everyting for you (all manufacturing cost , shipping cost , etc should paid as separate millstone so i would like milestone based payments (hardware design , Firmware ) you can View my work at my freelance profile and as weill https://elcoanlanka.com. I can start today. Contact me if you are interested Best Regards, Madushan

@electronicsdone

Dear Client, The hard part here is not reading a DHT22 or posting MQTT data. The hard part is making ESP32 + SIM7600G behave like a real low-power field device that survives weak cellular links and still meets the sleep-current target. I can help build this from hardware to firmware with the 24-hour bench test in mind from day one. My approach would be: ✅ design the schematic and PCB around ESP32, SIM7600G, DHT22, Li-Po charging/protection, USB-C, battery sensing, and clean modem power delivery ✅ write Arduino/C++ firmware for deep sleep, adjustable wake interval, MQTT publishing, SIM reconnection, failure logging, and battery health reporting ✅ prepare the Gerbers, source files, and test procedure so the device can be validated against 15-minute posting and low-sleep-current requirements For cellular IoT, the modem power path and reconnection logic matter more than fancy features. I would keep the design lean, testable, and field-oriented. One question: Do you already have the Supabase/MQTT authentication method and SIM APN/carrier details, or should the firmware stay configurable for those? If you message me, I can suggest the cleanest hardware/firmware split for a reliable first build. Best regards, Prat PCB Must Innovations

@Zainrais0786

Are you looking for a professional who can design a standalone ESP32 based temperature and humidity monitor that relies on 4G/LTE rather wifi. Ive got your back Hi, I am Zain. I can easily handle the task including • Embedded Systems • ESP32 / IoT / ESP IDF • Circuit Design • PCB Design • KiCAD / Altium • Firmware Development • C / C++ • Simulations etc. Lets chat. Best regards

@engrhasan01

I am Electrical and Pcb design Engineer.I have experience with ESP32 hardware, cellular IoT modules, MQTT systems, battery-powered embedded devices, and PCB design for low-power applications. For this project, I would focus on: • Ultra-low-power sleep design and power-path optimization • Stable SIM7600G communication and reconnect handling • Reliable MQTT posting to Supabase/PostgreSQL backend • Li-po charging, protection, and battery monitoring • PCB layout with proper RF, grounding, and power integrity practices Deliverables • Complete schematic (PDF + source files) • PCB layout + Gerber production files • Arduino/C++ firmware with: Deep sleep control Adjustable wake intervals MQTT communication LTE reconnect/error handling Battery health reporting • Basic documentation and test notes I can also suggest component/layout improvements to help achieve the <200 µA sleep-current target and improve long-term reliability. Best regards, Hasan

@Santoshchaulaga

Hello I have designed previously the exactly same board. So, I am applying for the job. I am Santosh Chaulagain, a professional Electrical Engineer and PCB Designer with over 7 years of experience in schematic design, PCB layout, and embedded systems, including ESP32, IoT devices, analog and digital circuits. I have successfully completed multiple projects for clients worldwide, delivering reliable and manufacturable designs. I have carefully reviewed your project requirements and I am confident that I can provide a high-quality solution tailored to your needs. My expertise includes PCB design using industry standards, component selection, BOM preparation, Gerber generation, and design optimization for cost and performance. I always ensure that my designs are fabrication-ready and tested for reliability. I focus on clear communication, timely delivery, and customer satisfaction. I am happy to discuss your project in detail and provide revisions until the final result meets your expectations. Looking forward to working with you. Best regards, Santosh C. Electrical Engineer | PCB Designer | ESP32 & IoT Specialist

@nichitav7

Hello I can deliver the complete low-power LTE telemetry system from hardware through production-ready firmware, with strong focus on ultra-low sleep current, network reliability, and long-term field stability. I have hands-on experience with ESP32 low-power design, cellular IoT devices, MQTT infrastructure, battery-powered embedded systems, and hardware bring-up including SIM7600-series integrations, PMIC tuning, OTA-safe firmware structure, and deep-sleep optimization. • Hardware / PCB: - Full schematic design (PDF + editable source) - 2~4 layer PCB optimized for LTE RF routing and low-noise power delivery - USB-C Li-Po charging + protection stage - Ultra-low quiescent current power architecture targeting <200 µA sleep - Battery voltage/current monitoring and health telemetry - Gerber, BOM, pick-and-place, manufacturing package • Firmware: - Production-grade Arduino/C++ firmware - ESP32 deep-sleep scheduling with configurable wake interval via serial - Reliable SIM7600G LTE initialization and watchdog recovery - MQTT publish pipeline to Supabase/PostgreSQL backend - Offline buffering + graceful reconnect handling - Failure logging and diagnostic reporting - Battery status + signal quality reporting - Fully documented source code I can also suggest several optimizations: - Replacing DHT22 with SHT31/SHTC3 for lower power and better accuracy - Load-switching the SIM7600G power rail during sleep Regards, Nichita.

@iAmiteshKr

Hi, I'm an embedded systems engineer with extensive experience designing hardware and firmware for both ARM Cortex-M (STM32, ESP32) and Cortex-A based systems. I can deliver a production-ready cellular sensor solution using KiCad for the full hardware design. My expertise includes: KiCad Design: Professional schematic capture and PCB layout, ensuring clean power rails and optimized signal integrity for the SIM7600G. Hardware: Expert-level design for ESP32 and STM32 platforms, focusing on ultra-low-power battery management (sub-200µA sleep targets). Cellular & Sensors: Direct experience interfacing DHT22 sensors and 4G/LTE modules with robust Li-po charging and protection circuits. Firmware: Development in C/C++ (ESP-IDF/Arduino) with reliable MQTT routines for data transmission to Supabase/Postgres. I have built similar remote monitoring systems and can provide the source files and Gerbers needed for immediate production. I am ready to complete the 24-hour bench run to ensure 100% stability.