ATmega328P + ARM Cortex-A7 = Akarel

Akarel – which recently surfaced on Indiegogo – is a hardware development kilt that integrates Atmel’s ATmega328P microcontroller (MCU) and a 1GHz Allwinner A20 dual-core ARM Cortex-A7 processor (CPU) on a single board with a touch screen.

As Akarel creator Karel Kyovsky notes, the platform is targeted at devs and Makers who require a touch screen interface to implement their respective projects.

The development platform is currently available in two iterations: Akarel 7 (7-inch display) and Akarel22 (22-inch display). The former features an industrial grade projected capacitive multi touch connected via I2C, while the latter is equipped with a USB-linked capacitive single touch.

“Some development kits are missing displays or touch, [while] others use obscure software stacks. Imagine implementing your hack ideas within hours instead of days like you’ve been doing until now,” Kyovsky explained.

“Akarel integrates Android OS running on [the] ARM Cortex A7 via UART, with Arduino software running on [Atmel’s] ATmega328P MCU. Integration and connection of both chips on [a single] PCB [offers a number of] advantages.”

According to Kyovsky, these include:

• 

Graphics and UI capabilities of Google’s flagship Android OS
• Optimized environment for application development
• Seamless network connectivity via WiFi or Ethernet
• Access to extensive Arduino community libraries

Kyovsky says he envisions Akarel being used to develop smart home automation and security systems, kiosks/payment terminals, along with Internet of Things (IoT) devices and appliances.

On the software side, the Akarel kit offers Makers and developers access to a Git repository stocked with Uboot source code, Linux kernel source (3.4.39), fine-tuned Android OS sources (4.2.2), Arduino firmware sources, Arduino tools (i.e. avrdude) and example apps.

“We want you to concentrate on writing an application not on spending time to make the basic things work. We have done it for you already. And if you want to dive deeper and modify the Linux kernel or Android OS…Why not? You have all the sources available for you to change and compile,” Kyovsky added.

“In order to save you from the hell of installing all the toolchain (correct version of gcc, libs, headers, automake, make, java, you name it) we have also prepared a Ubuntu virtual machine for you which may be downloaded and which has [the entire] toolchain preinstalled so that you can start recompiling your complete stack within a few minutes.”

Interested in learning more about the Akarel? You can check out the project’s official Indiegogo page here.

Integrating Capacitive Touchscreens Into Automotive Dashboards

By Stephan Thaler and Thomas Wenzel

As automotive design engineers integrate more sophisticated touchscreen technologies into their vehicles, they are transforming the driver experience. Resistive touchscreens were once the predominant choice because they are easy to control and relatively inexpensive to manufacture. However, they also support lower light transmission and their surfaces are sensitive to scratching. Capacitive touchscreen technology overcomes many of the problems associated with resistive touchscreens, while bringing the familiar advantages of smartphones and tablets.

When a finger approaches the surface of a capacitive touchscreen, this leads to a slight change in capacities of one or more of the underlying sensors. Self-capacitance and mutual capacitance are two ways to map capacity. The self-capacitance method measures the input signal of a complete row and column of electrodes; however, this method doesn’t always unambiguously classify the position when operated with more than one finger. Mutual capacitance measures every point of intersection in the orthogonal mix. Given this, you can exclude gaps in the finger classification that would be visible on the screen. 

When a finger approaches the surface of a capacitive touchscreen, this creates a slight change in the capacities of one or more of the sensors in the screen.

Unlike resistive technology, with capacitive technology the user’s finger doesn’t need to exert any pressure on the screen surface in order to be recognized. The precise position of the fingers on the touchscreen is calculated when the measured values of all points of the intersection are evaluated. Sensitive touchscreen controllers, such as Atmel maXTouch devices, can even register the approach of one or more gloved fingers.

Since capacity changes in these applications is very small, it’s critical to minimize the impact of noise and interference. Algorithms in the touchscreen controller can address these issues. For example, maXTouch controllers offer interference suppression that allow you to significantly reduce the number of sensor layers above the LCD screen. Post-processing functions also are integral to reliable operation, especially in different environmental conditions.

To learn more about automotive touch displays, read our full article, Capacitive Touch Technology Opens the Door to a New Generation of Automotive User Interfaces.