HwUI is an open source, low cost, single PCB board with integrated capacitive touch buttons and sliders in addition to a micro-controller and Bluetooth module. It’s perfect for rapid prototyping or incorporating into your own projects in need of a user interface. For automation engineers, HwUI can serve as both product motherboard and user control panel in a single PCB. For music enthusiasts, HwUI is a Bluetooth audio development board with stereo audio and FM which can pair with your mobile phone. Using HwUI makes product design with plastics more flexible, and waterproofing simpler. The HwUI platform also includes open source micro-controller firmware and a Python-based GUI for PC.

Who Needs It and Why?

• Product developers: Provides a single PCB for any product needing a micro-controller, Bluetooth, and user interface.
• Music system developers: Provides Bluetooth audio integrated with FM, SD card, IR, and USB.
• Product companies: Allows rapid development of products with open source hardware and firmware.
• Automation and test bench developers: HwUI PC GUI can be the starting point for your custom GUI for automation and test bench projects.
• Hobbyists: Develop useful home products such as a pet feeder or a Bluetooth electric touch switch board.

Features & Specifications

-* Dimesnions may differ slightly in the next revision.

Block Diagram

Where Are We?

The first revision of the board is complete. This revision has a few minor issues and requires modifications which are listed below. These corrections and modifications will be addressed in the next revision which will be used for production.

• This series of Cypress chip does not support touch sensor diplexing which was a design mistake from our side. Due to this error, the bottom half of the radial slider and the left half of linear slider is not functional in the current iteration. The board will be modified to have five double-sized sensor pads in place of the current ten for each radial and linear slider. The overall size of each slider will remain the same.
• An SMD connector instead of through-hole is needed to give a flat surface on the touch side.
• LED drill hole size has to be corrected for proper LED assembly.
• Power input is currently 3.3 V. This will be changed to 5-12 V by adding a DC-DC regulator.
• BT53 Bluetooth module will be replaced with Beken BK3254 module

Firmware and software have been succesfully tested with UART-USB as depicted in the video. Bluetooth integration is in progress.

Open Source Software & Hardware

Schematics, Gerber files, board files, firmware, and software will be published in GitHub once the campaign is complete. We welcome contributors. HwUI is completely open source and free to use for commercial use provided that the same board will not be sold as a prototyping board.

Capacitive Touch Sensors

HwUI incorporates a radial slider, linear slider, proximity sensor, and six touch buttons which can be configured based on the developer’s needs. The proximity sensor is multiplexed with a touch button. The Cypress cap sense controller has an auto tuning feature which helps us to use most of the plastic/glass materials without reprogramming the cap touch settings. Sliders can be used for adjusting parameters like volume, temperature, time duration, etc.

Micro-controller

A micro-controller configures and controls the cap touch controller and communication to PC via UART (UART to USB). For a low cost MCU, it supports a rich peripheral set such as UART, I2C, SPI, GPIO, ADC, and RTC. Peripheral pins are exposed on the connector for developing custom applications. Documentation will be provided to start with firmware development and example code will be provided for common use cases.

Bluetooth

BK3254, a Bluetooth 4.1 Audio/IO module, will be used in the second revision to make the design more affordable. It supports audio out, audio input, FM, SD card, IR remote control, and easily pairs with a mobile phone. It also supports GPIO, and serial peripherals. The Bluetooth module can be controlled by UART commands from the MCU, although the cap sense IC can be directly connected to the module without the MCU. Bluetooth GPIO and serial peripherals can be controlled via AT commands. The Bluetooth module SDK is the manufacturer’s, and is proprietary and not open source.

PC Software

The HwUI platform includes a basic GUI written in Python for Windows. The GUI can help log user responses and control the GPIO’s or other peripherals on the board. It currently supports the UART-COM port interface for communicating with the board (requires external UART to USB converter). Bluetooth integration is under development. Documentation will be provided to understand and modify the code for custom requirements.

HwUI's Python GUI

Development Tools

HwUI Board will be shipped with preloaded code which can act as either a Bluetooth audio system, cap sense event output via UART/Bluetooth, or simple GPIO control based on touch events. For custom designs, the micro-controller needs to be programmed using the free/evalution IDE STM32cubeMX and Keil. The available programming interfaces are ST-LINK/V2 ($21) or STM32 discovery kit. The GUI code is in Python (Windows). The hardware design was done in ORCAD/Allegro.

Stretch Goals

A Bluetooth Android app and a small form factor music board will be developed if the funding level during crowdfunding surpass’ $5,000. Moving forward, number keypad units, a triac based switch board, ultra low cost Bluetooth audio module, and many other designs for the HwUI platform are planned for development. Our goal is to create an eco-system of open source, manufacturer friendly, ready-to-use modules and designs to make product development quicker.

Manufacturing Plan

A batch of 100 boards will be manufactured once the second hardware revision is successfully tested. This batch size is needed to keep HwUI affordable. Manufacturing will be carried out by known EMS vendors in Bangalore, India.

Shipping & Fulfillment

Fulfillment of the HwUI pledges will be handled by Crowd Supply from their Portland, OR warehouse. Please have a look at this useful page about ordering, paying, and shipping for more information.

Risks & Challenges

The first revision of the board has been successfully tested. The addition of the BK3254 module in the second revision does not pose a significant risk since it is a ready module. A usual procurement delay has been added to the schedule to accommodate lead time and custom clearance delays. Manufacturing does not pose any significant risk since there are no fine pitch or BGA IC/connectors.