Set up Otii hardware, either the Otii Arc Pro or Otii Ace Pro, to work as a power source box providing constant voltage to the DUT, ranging from 0.5V-5V / 0V-25V, and enable it to measure output current and voltage.

Products required

Otii hardware setup

1. Connect Otii hardware to your computer via USB. If needed, add a DC power supply via the DC plug.

2. Connect Otii hardware’s banana connector positive lead to DUT positive (+) battery connector/power connector.

3. Connect Otii hardware’s banana connector negative lead to DUT negative (-) battery connector/power connector (GND).

Otii software setup

1. Open the Otii 3 Desktop App, then select "Create a new Otii Project."

2. In the left sidebar, find the CONTROL section. Within this section, add the Otii hardware identified by your computer. Just click the add button on the right side of the hardware identified.

3. Considering the DUT's power ranges, set the required voltage for the added Otii hardware in the voltage box located on the left side of the power supply button.

4. Under "General Settings," make sure that the "Power Box" option is selected, and set an OC (overcurrent) protection for the DUT.

5. Under "Channels", select "Main current" to measure DUT's output current and "Main voltage" to measure DUT's output voltage. The "Main power" channel is assigned by default when the main current is selected to measure DUT's energy consumption.

6. [Optional] The previously selected channels will be listed under the MEASUREMENTS section. In this section, the sampling rate, up to 50 ksps, can be set. (Only possible with the Otii Ace Pro)

7. Click the record button in the upper left corner of the toolbar to start recording DUT measurements. Since your DUT is not powered on yet, only noise measurements will be observed at first.

8. Turn on the DUT by clicking the power button next to the desired voltage assigned. Once turned on, the DTU measurements are being recorded.

9. Now, it's time to validate, analyze, and optimize your embedded system or IoT devices.

Keep in mind

🔋 Use wires with the lowest possible resistance and keep them as short as possible to minimize voltage drop, especially when the DUT consumes high current. The resistance in wires will be added to the total series resistance within the system, causing an unwanted voltage drop and an error in power and energy consumption measurements.

🔋 If the DUT consumes high current during power-up, causing high voltage drops in the attached wires, which directly affects the power-up cycle of the DUT since the voltage is too low. In case of experiencing this, connect one or several capacitors from Bat+ to Bat- on the DUT side to stabilize the voltage to start up the DUT properly. Note that the Otii Arc and Otii Ace have very low output capacitance for being a power source for the DUT but also a programmable load.

The connection of the Otii hardware—either Otii Arc Pro or Otii Ace Pro—is required as a starting point for working with the Otii Product Suite. This connection must be to the Device Under Test (DUT) or the battery to be validated and to a computer running Otii Software, Otii 3 Desktop App.

Go to the Qoitech Download page to download and install the latest Otii 3 Desktop App version for your preferred operating system (OS). Refer to the "Install Otii software" page for step-by-step instructions on installing and setting up the Otii 3 Desktop App for the different OS supported.

To start in just a matter of minutes, make sure to have:

• A computer with at least an available USB port running the Otii 3 Desktop App. It is recommended at least 16 GB of RAM.

• The DUT to be measured, analyzed and optimized.

• Positive and negative banana connectors for connecting the Otii hardware to the DUT.

• Female to female/male jumper wires for connecting the Otii hardware main expansion port to the device under test for extra capabilitites.

• [Optional] External DC adapter. For Otii Arc Pro, in the range 7-9V, max 5A. For Otii Ace Pro, in the range 7-20V, max 5A. Here are a few suggestions on the DC adapters.

Learn more about

As shared on the Otii Ace Pro page, this version is the big brother of the Otii Arc Pro. Keeping the same portable and compact form with comprehensive technical features for energy optimization but with enhanced capabilities to boost battery-driven and energy-harvesting devices requiring high precision at higher voltage ranges, with a high sample rate and low step size.

It is an all-in-one tool with an isolated power supply unit, a constant voltage/current source and sink, and a high-precision multichannel multimeter. Making it a power analyzer/profiler that records and displays currents, voltages, and power measurements in real time. Enabling hardware, firmware, and software developers to optimize the energy consumption and battery life on any device under test.

With Otii Ace Pro and Otii 3 Desktop App, you can source the voltage of the device under test (DUT) up to 25V while simultaneously measuring and recording current, voltage, and power data in real-time for further analysis to optimize battery life throughout the development cycle.

Hardware overview

The front side of the Otii Ace Pro has the main connectors, additional ports to extend measurement capabilities, plus a status LED.

The back side of the Otii Ace Pro has the host USB connector and an input socket to power up the unit with an external DC adapter when required.

Main connections

The Otii Ace Pro has the voltage(+) and voltage(-) binding post (red and black connectors located on the right side of the instrument), which are used to source the DUT but also to measure the current, voltage, and power of the device. The DUT can be connected through its battery connectors or DC input; refer to the connection diagram below for better understanding.

To power up the Otii Ace Pro and enable the communication with the host computer, use the provided USB C to USB C cable to connect the unit to your computer.

Check out the Wiring up page to explore all possible connection configurations between the Otii Ace Pro and your DUT.

Expansion Port

The expansion port on the front of the Otii Ace Pro is designed to enhance the hardware's functionality, allowing users to measure additional voltages and currents or trigger external events. These additional pins feature multi-input and multi-output for analog and digital signals, serial communication, and additional power and ground points. Below is a general overview of the additional pins available:

Status LED

The table below explains the Otii Ace Pro's status LED behaviors and their meanings to help you quickly identify the device's state.

Otii hardware features two main connectors and one expansion port. Multiple channels can be measured with the available inputs, such as main current, main power, main voltage, ADC current, ADC voltage, SENSE+ voltage, SENSE- voltage, GPI1, and GPI2, as well as capturing serial logs from any embedded system or IoT devices.

To get the most out of the Otii Arc Pro and Otii Ace Pro, start by checking out the Expansion port to explore how to enhance measurement capabilities.

Wiring up possibilities

Discover hardware setup examples for a variety of use cases:

Keep in mind

Selecting a power supply

When using an external DC adapter, choosing one from an established supplier is highly recommended. The adapter should be low-noise, comply with IEC 60950-1 as a Limited Power Source, and have an output of 7 to 9 VDC for the Otii Arc Pro and 7 to 20 VDC for the Otii Ace Pro, with a maximum of 5A.

Visit the FAQ page for more information on selecting the proper power supply.

Grounding advice

A separate ground wire for the signal ground, attached to either DGND (Digital Ground) or AGND (Analog Ground) on the expansion port, should be used. This will prevent disturbances and measurement errors caused by voltage drops in the negative battery wire.

• AGND is utilized as a reference point for analog measurements.

• DGND is used as a reference point for digital signaling.

Set up Otii hardware, Otii Arc Pro, or Otii Ace Pro to capture logs from the DUT serial log.

Products required

Otii hardware setup

2. Connect Otii hardware’s banana connector positive lead to DUT positive (+) battery connector/power connector.

3. Connect Otii hardware’s banana connector negative lead to DUT negative (-) battery connector/power connector (GND).

4. Connect Otii hardware's RX pin to the DUT TX pin.

5. Connect Otii hardware's DGND to the DUT GND pin.

Otii software setup

1. Open the Otii 3 Desktop App, then select "Create a new Otii Project."

2. In the left sidebar, find the CONTROL section. Within this section, add the Otii hardware identified by your computer. Just click the add button on the right side of the hardware identified.

3. Considering the DUT's power ranges, set the required voltage for the added Otii hardware in the voltage box located on the left side of the power supply button.

4. Under "General Settings," make sure:

   • "Power Box" option is selected.

   • Set digital voltage according to the DUT's digital voltage level for the UART

   • Set an OC (overcurrent) protection for the DUT.

5. Under "Channels," choose the measurements desired to be recorded (e.g., main current, main voltage, main power, among others)

6. Under "UART", make sure:

   • Assign the DUT's baud rate.

   • Select "UART log" to enable the serial communication. Once enabled, the console log will automatically open.

7. Click the record button in the upper left corner of the toolbar to start recording DUT measurements. Since your DUT is not powered on yet, only noise measurements will be observed at first.

8. Under the CONTROL section, turn on the DUT by clicking on the power button located right next to the desired voltage assigned. Once turned on, the DTU measurements are being recorded.

9. Now it's time to validate, analyze, and optimize your embedded system or IoT devices.

If the Device Under Test (DUT) needs to be powered from an external source while still measuring system current and voltage, an external shunt resistor connected to the ADC inputs of the Otii hardware, whether the Otii Arc Pro or Otii Ace Pro, can manage this.

Products required

Otii hardware setup

2. Connect the external shunt resistor in series between the external power supply's positive (+) line and DUT's positive (+) battery connector.

3. Connect ADC+ and ADC- across the resistor to measure the voltage over the resistor.

4. Connect Otii hardware's AGND to the DUT's GND.

Otii software setup

1. Open the Otii 3 Desktop App, then select "Create a new Otii Project."

2. In the left sidebar, find the CONTROL section. Within this section, add the Otii hardware identified by your computer. Just click the add button on the right side of the hardware identified.

3. Under "General Settings," make sure:

   • "Power Box" option is selected.
4. Under "Channels," select "ADC current" to measure the current over a shunt resistor. In the case of measuring voltage over the shunt resistor, the "ADC voltage" must be selected as well.

5. [Optional] The previously selected channels will be listed under the MEASUREMENTS section. In this section, the sampling rate, up to 50 ksps, can be set. (Only possible with the Otii Ace Pro)

6. Click the record button in the upper left corner of the toolbar to start recording DUT measurements. Since your DUT is not powered on yet, only noise measurements will be observed at first.

7. Under the CONTROL section, turn on the DUT by clicking the power button. Once turned on, the DTU measurements are being recorded.

8. Now it's time to validate, analyze, and optimize your embedded system or IoT devices.

Keep in mind

🔋 The voltage over the shunt resistor is measured differentially. No extra signal ground is needed if you only want to measure the current.

🔋 If voltage measurement is required, it is measured between ADC+ and AGND. In this case, AGND needs to be connected to the ground of the DUT.

As shared on the Otii hardware page, these products are designed for accurate and extensive energy optimization for battery-driven and energy-harvesting devices. Featuring a power supply, a current and voltage measurement unit, and a data-acquisition module, all housed in one compact, portable form factor.

Below are the full technical specifications for the Otii Arc Pro and Otii Ace Pro. Refer to them to make sure you are matching the right Otii hardware with your devices under test (DUT)

Set up Otii hardware, Otii Arc Pro, or Otii Ace Pro to measure a subsystem current and voltage over a shunt resistor in addition to measuring the complete system. Note that the resistor can be part of the actual system or applied externally.

Products required

Otii hardware setup

1. Connect Otii hardware to your computer via USB. If needed, add a DC power supply via the DC plug.

2. Connect Otii hardware’s banana connector positive lead to DUT positive (+) battery connector/power connector.

3. Connect Otii hardware’s banana connector negative lead to DUT negative (-) battery connector/power connector (GND).

4. Connect Otii hardware's ADC+ and ADC- across the shunt resistor for current measurement; no additional ground is needed for this. Make sure to connect the shunt resistor side with the high side to ADC+ and the one with the low side to ADC-. Note that if negative currents are measured, the high side has a lower potential than the low side.

5. [Optional] To measure voltage, connect AGND to the DUT's ground and measure the voltage between ADC+ and AGND.

Otii software setup

1. Open the Otii 3 Desktop App, then select "Create a new Otii Project."

2. In the left sidebar, find the CONTROL section. Within this section, add the Otii hardware identified by your computer. Just click the add button on the right side of the hardware identified.

3. Considering the DUT's power ranges, set the required voltage for the added Otii hardware in the voltage box located on the left side of the power supply button.

4. Under "General Settings," make sure:

   • "Power Box" option is selected.

   • Set an OC (overcurrent) protection for the DUT.

   • Set the value of the shunt resistor in the "ADC resistor" field. Check how to choose the resistor if you are not sure how to do it.

5. Under "Channels," select "ADC current" to measure the subsystem current over a shunt resistor. In the case of measuring voltage, the "ADC voltage" must be selected as well. If the system itself needs to be measured, it can also be measured; select the channels desired to be measured in addition to the ones previously selected.

6. [Optional] The previously selected channels will be listed under the MEASUREMENTS section. In this section, the sampling rate, up to 50 ksps, can be set. (Only possible with the Otii Ace Pro)

7. Click the record button in the upper left corner of the toolbar to start recording DUT measurements. Since your DUT is not powered on yet, only noise measurements will be observed at first.

8. Under the CONTROL section, turn on the DUT by clicking on the power button located right next to the desired voltage assigned. Once turned on, the DTU measurements are being recorded.

9. Now it's time to validate, analyze, and optimize your embedded system or IoT devices.

Keep in mind

🔋 The voltage over the shunt resistor is measured differentially. No extra signal ground is needed if you only want to measure the current.

🔋 If voltage measurement is required, it is measured between ADC+ and AGND. In this case, AGND needs to be connected to the ground of the DUT.

How to choose the resistor

For Otii Arc Pro

The differential input voltage range for the Otii Arc Pro ADC inputs goes from -81.9175 mV to 81.92 mV. Based on these values, the absolute maximum (peak) current through the sensing resistor must be determined.

Remember that by using Ohm's Law (V = I x R | I = V / R | R = V / I), the relationship between voltage, current, and resistance in an electrical circuit can be determined.

Here's an example to illustrate how to choose the resistor:

Suppose the system has a maximum peak current of 200 mA. By calculating, 0.08192 V / 0.2 A, the resistor value is equal to 0.41 ohms. But, the closest standard resistor value is 0.39 ohms. Resulting in a measuring range of 0.08192 V / 0.39 ohms = 0.210 A.

In conclusion, a 0.39 ohm sensing resistor will result in a measurement range of +/- 0.210 A.

For Otii Ace Pro

Following the same example as above, let's do the same for now but for the Otii Ace Pro.

The differential input voltage range for the Otii Ace Pro ADC inputs goes from -102.4 mV to 102.4 mV. Based on these values, the absolute maximum (peak) current through the sensing resistor must be determined. Here's an example to illustrate how to choose the resistor:

Suppose the system has a maximum peak current of 200 mA. By calculating, 0.1024 V / 0.2 A, the resistor value is equal to 0.512 ohms. But, the closest standard resistor value is 0.51 ohms. Resulting in a measuring range of 0.1024 V / 0.51 ohms = 0.200 A.

In conclusion, a 0.51 ohm sensing resistor will result in a measurement range of +/- 0.200 A.

The expansion port on the front of the Otii hardware is designed to enhance the hardware functionality, allowing users to measure additional voltages and currents or trigger external events. These enable complex testing setups, allowing users to expand measurement capabilities beyond standard power analysis, offering flexibility across diverse use cases from development to debugging.

Fourteen additional pins are available on the expansion port, which features multi-input and multi-output for analog and digital signals, serial communication, and additional power and ground points. Depending on the project requirements, these pins can be easily enabled and set up as needed within the Otii 3 Desktop App.

Note that the expansion port is designed to be identical across the Otii hardware versions, but capabilities in terms of voltage range, impedance and resolution differ from one version to the other.

As shared on the , this is a compact and portable tool with comprehensive technical features for energy optimization of battery-driven and energy-harvesting devices. As a multi-purpose tool, it serves as a power supply, measurement unit, analyzer and debugger, making it the must-have addition for everyday use on any hardware, firmware and software developer’s desktop.

With Otii Arc Pro and Otii 3 Desktop App, you can source the voltage of the device under test (DUT) up to 5V while simultaneously measuring and recording current, voltage, and power data in real-time for further analysis to optimize battery life throughout the development cycle.

Hardware overview

The front side of the Otii Arc Pro has the main connectors, additional ports to extend measurement capabilities, plus a status LED.

The back side of the Otii Arc Pro has the host USB connector and an input socket to power up the unit with an external DC adapter when required.

Main connections

The Otii Arc Pro has the voltage(+) and voltage(-) binding post (red and black connectors located on the right side of the instrument), which are used to source the DUT but also to measure the current, voltage, and power of the device. The DUT can be connected through its battery connectors or DC input; refer to the connection diagram below for better understanding.

To power up the Otii Arc Pro and enable communication with the host computer, connect the unit to your computer using the provided micro USB to USB A cable.

Expansion Port

The expansion port on the front of the Otii Arc Pro is designed to enhance the hardware's functionality, allowing users to measure additional voltages and currents or trigger external events. These additional pins feature multi-input and multi-output for analog and digital signals, serial communication, and additional power and ground points. Below is a general overview of the additional pins available:

Status LED

The table below explains the Otii Arc Pro's status LED behaviors and their meanings to help you quickly identify the device's state.