EasyVolts – regulated power supply, UART, RS485 and GPIO for DIY and professionals controlled by USB

Overview

EasyVolts is an adjustable power supply that takes 5V DC from USB and converts it to any desired voltage in the range from 0 to 24V. The onboard DC-DC converter allows us to use almost all power that can be taken from USB2.0. EasyVolts has embedded microcontroller responsible for output voltage and current limit control over USB. It also provides additional functionality. Depending on selected configuration it can be “USB-RS485 converter + 2 GPIO/PWM pins” or “USB-UART converter”. When the device is connected to USB it appears on PC as two virtual COM ports. One is used to control power supply and GPIO, the second – as “USB-UART/RS485” adaptor. Such design lets you control this device easily with any software that can communicate over COM port, including your own programs or scripts. Pinout2

Various demo videos:

Python-based software i2c master using EasyVolts.

EasyVolts as a Digital input and PWM output for a Python script on PC.

EasyVolts as PC controlled PWM source.

PC controls OLED display with EasyVolts.

*the GUI tool for EasyVolts can be downloaded here: EasyVolts_GUI_WINDOWS.

Technical parameters of the power supply:

Output voltage: 0-24V.

Max output current: 1A.

Max output power: ~2W*(up to ~4W for USB3.0 or high power USB2.0).

Voltage resolution: <50mV.

Current resolution: <2mA.

Noise: ~200mVpp

* – this is an important parameter because according to USB2.0 specification its maximum power is limited to 2.5W(but it can provide up to ~4W when connected to USB3.0 or high power USB2.0). DC-DC converter efficiency is high so we can deliver ~60-90% of input power (depends on the selected output voltage and load). It means that max output current at 24v will be ~0.06a and at 3.3v it will be ~0.55a. For more details check this post.

Technical parameters of embedded USB-UART/GPIO converter:

Logic levels: 3v3.

UART speed: 300-230400 bit/sec.

The internal resistance of Rx and Tx pins: ~300 ohm.

Possible “Tx” pin mode: UART_TX/active low/active high/Z-state(with or without pullUp/pullDown)/PWM(pushPull)*

Possible “Rx” pin mode: UART_RX/active low/active high/Z-state(with or without pullUp/pullDown)/PWM(pushPull)*

PWM base frequency: 240kHz.

PWM frequency division configuration: 1-65535 (PWM frequency 240kHz – 3.66Hz).

PWM duty cycle resolution: 0.5%.

*- logic level of the pin in active_low/active_high/Z_state can be read by the host, so it provides all possible read/write pushPull/openDrain GPIO functionality.

How it can be used

1) As a “power+communication” tool for professional engineers. With EasyVolts you can connect various devices to your laptop and work with them everywhere or even remotely.

2) For DIY and hobby – because it can be simply controlled through COM port. Just connect your load (LED, relay, motor or whatever you want to control), plug it in USB port (it can be your laptop or even RaspberryPi) and that’s it! Now you can control your load either manually (with any COM port terminal program) or automatically (using a script or your own software). Just send a textual command to EasyVolts and it will change a brightness of your LED or start motor or switch relay. Just that simple!