09 April 2019

Prolong the battery life of your next IoT device using OTII ARC - intelligent power supply with built-in consumption meter



The development of a battery powered device necessarily takes place through a process of measuring its consumption, which is usually protracted and difficult to reproduce due to the different modes of operation. This is especially difficult in IoT projects where consumption changes from units of micro amps to several amps.

Current tools for analyzing power include multimeters and oscilloscopes. Multimeters are great for getting a bead on the average current consumption. However, they lack the resolution to see fast transients and currents down to the nanoamp range, which is where low-power designs are headed. For their part, oscilloscopes it’s difficult to get access to a trace with a ‘scope, and not all scopes allow display and correlation between executed code and the actual line voltages, current and signals. There’s also the problem of ensuring the ‘scope has enough memory to store the data. Moreover, both multimeters and ‘scopes often require the user to pause to adjust the range as currents or voltages rise and fall.

Well, thanks to the Swedish company Qoitech and their Otii Arc Energy Monitor, this task is now easy to implement with minimal investment.

The Otii Arc is essentially a lightweight, portable, smart power supply. It contains two banana jack plugs that can be used to power an embedded system from 0.5 to 5.0 volts. The Otii Arc can supply the system with up to 250mA of current when powered through USB, or up to 5A if supplied with an external 7.5 to 9.0V supply. What makes the Otii Arc interesting is that not only is the output voltage configurable, but it contains several analog and digital sensors that can be used to sample voltage and current at 4 ksps.

First, the main banana jack plugs can be used to measure system supply currents ranging from 1uA up to 5A. This allows developers to closely monitor their system energy consumption. The 14-pin expansion connector includes a second current sensor that can be used to probe shunt resistors on the board. This could be used to monitor electrical subsystems such as the microcontroller, RF circuits, or the power supply circuits. The expansion connector also provides developers with useful features such as a UART transmit and receive along with some general-purpose inputs and outputs.

Thus far, the Otii Arc has turned out to be a very useful and interesting instrument to add to your energy optimization toolkit. The fact that it can be powered over USB, coupled with it being light and very portable, makes it easy to travel with and super simple to setup.

Otii Arc basic functions:

  • Intelligent power supply with output voltage up to 5V and output current up to 5A;
  • Precision consumption measurement ranging from 1uA to 5A with 4ksps sample rate;
  • Additional differential input for switching shunt resistor with measuring range up to +/- 82mV 4ksps sample rate;
  • 2 digital inputs + 2 digital outputs with programming capability;
  • UART Interface (Rx / Tx) with synchronous recording capability;
  • Opportunity to simulate standard battery types*;
  • Ability to measure and record the characteristics of non-standard batteries and subsequent simulation*;
  • Running scripts to automate the measurement process*;
  • User-friendly software that is compatible with Windows, Linux and MacOS;
  • Energy measurement function;
  • Compact size.

* Some features require an additional license

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