Building an IoT device usually moves through seven stages: define the problem, prove the idea, build a working prototype, test it in the field, redesign it for manufacturing, check approvals, then produce, deploy and support it. Many projects stall because people treat the first working prototype as the finished product. A circuit that works on a desk for a week is very different from a device that runs for years in a shed, a factory or a customer's home.

Why a prototype is not a product

A prototype answers one question: "can this work?" A product has to answer harder ones. Will it keep working in heat and damp? Can someone else install it? What happens when the internet drops? How will it be updated and repaired? Can you make many identical units? Each stage below closes part of that gap.

Stages 1 and 2: from idea to proof of concept

1. Define the problem and the requirements

Write down what the device must measure or control, where it will live, how it gets power, how it connects, who will use the data and what "working" means. Include the boring details too: how long between battery changes, what the alert should say, and whether it should be in Bangla or English. When I start a project, this one page usually saves more time than anything else.

2. Proof of concept

Using development boards such as an ESP32, Arduino or Raspberry Pi and off-the-shelf sensors, you check the core idea. Can the sensor detect what you need? Can the data reach a phone? At this stage, changes are quick and cheap. The ESP32, Arduino and Raspberry Pi article explains how those boards differ.

Stages 3 and 4: prototype and field pilot

3. Working prototype

The parts move from loose wires to something closer to the real device: a first custom circuit board, an enclosure, proper firmware that handles errors, and a basic dashboard. It looks and behaves like the product, even if it is still assembled by hand.

4. Field pilot

A small number of units go to real sites for several weeks or a full season. This is where you learn what the lab never shows: dust in connectors, weak signal behind a wall, staff unplugging the device to charge a phone, a sensor that slowly drifts. Treat the pilot as research, not as a sale. The IoT pilot project page describes how to run one.

Stages 5 and 6: design for manufacture and approvals

5. Design for manufacture

Lessons from the pilot go into a revised design that can be built the same way every time: a circuit board a manufacturer can assemble, parts that are available and not about to be discontinued, an enclosure that is easy to assemble and seal, and a test procedure so that every unit is checked before it leaves. The firmware also needs a way to be updated in the field; see over-the-air firmware updates.

6. Approvals and compliance

Devices that use radio, run on mains power or are sold to the public may need approvals, both in Bangladesh and in any country you export to. Requirements depend on the product and change over time, so check with the relevant regulator or a compliance specialist early, not after production. Using pre-certified radio modules can simplify this, but it does not remove the need to check.

Stage 7: production, deployment and support

Small batches come first. Each unit is tested, labelled and registered, so you know which firmware version it runs and which customer it belongs to. Then come installation guides, training for whoever installs and uses it, spare parts, a way to report faults and a plan for updates. Support is a stage in its own right, not an afterthought: a device that stays in the field for years will need attention.

Common mistakes

  • Skipping the pilot and producing many units straight from a lab prototype.
  • Choosing parts that are hard to buy locally or may soon be discontinued.
  • Having no plan for firmware updates, so every bug fix needs a site visit.
  • Ignoring power cuts and voltage swings until devices start failing.
  • Leaving security for later. Default passwords and unencrypted connections are hard to fix after deployment; see IoT security basics.

Before you start

  1. Write a one-page requirement: the problem, the site, power, connectivity and users.
  2. Allow time for a field pilot through the toughest season.
  3. Ask early about approvals for every market you plan to sell in.
  4. Decide who will support the devices after installation.

If you have an idea at the prototype stage, I am happy to look at it with you; see the IoT development service.

Related service IoT device development Connected devices from prototype to dashboard: sensors, firmware, connectivity and alerts that reach your phone.