Davide Orengo's Pulse Counter Taps an ESP32-S3 and LTE Modem to Track and Report Utility Usage

Connecting to as many as 10 meter pulse outputs, this multi-sensor tracking system sits on a DIN rail and keeps a running tally of usage.

Hardware engineer and self-described electronics enthusiast Davide Orengo has designed a DIN rail-mountable Espressif ESP32-powered device for reading the pulses from energy and other meter systems — automatically calculating consumption and transmitting it to a central database over a cellular link.

"In today's world, gaining control over energy consumption is a top priority. There are two main methods for monitoring domestic energy use," Orengo explains. "Current phase measurement using a clamp meter [and] in-line meters. Both methods often offer an interface with a pulse output, where the pulse frequency is directly proportional to the real-time energy consumption. This allows for easy data collection and analysis."

It's this pulse output that Orengo taps with his creation, built around an Espressif ESP32-S3 microcontroller. Connecting to the open-drain pulse output available on a range of energy and other utility meters with a pull-up resistor, the gadget can detect each electrical pulse as the meter ticks over — which, with knowledge of when a pulse is triggered, can be used to calculate real-world usage.

"Consumption is directly proportional to the frequency of pulses," Orengo explains. "Therefore, by defining a time window and counting the number of impulses that occur, it's very simple to estimate the instantaneous consumption at that particular moment by calculate the mean frequency of pulses. By continuing this operation over time, it is possible to determine both the total consumption and how it has changed over time."

The system, configurable for different pulse frequencies, calculates the usage over a 30-minute window from up to 10 independent sensors. This is then transmitted on a configurable interval to a cloud database over a 4G LTE cellular modem — which also provides remote control capabilities, through simple SMS messaging.

The project is documented in full on Hackaday.io; a prototype has been proven, with Orengo now awaiting a custom PCB version for testing.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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