Development kit streamlines control of color HMIs
There was a time users only expected to see sophisticated graphical interfaces on high-end devices. Today, they want color HMIs even on products that only a few years ago sported simple segment displays, like white goods, coffee machines, and multifunction printers. The trend makes sense¾color displays enhance the user experience and ease of use, offering a differentiating feature for the manufacturer. For cost-sensitive applications, though, especially in the low-end sector, the shift also poses a challenge to design engineers, who must develop new designs without changing much in the cost or hardware design structure. The solution comes in the form of the FMcolor, a targeted development kit that augments an ARM-based MCU with firmware and pre-program modules that free embedded engineers to focus on the specific value propositions of their products, simplifying integration, lowering costs, and speeding time to market.
Color displays made easy
Historically, color LCDs required a dedicated graphics controller. This added another component to the system, increasing cost, size, and power consumption, as well as complexity in terms of integration and programming. For high-margin products like smart phones, cameras, and computers, this made sense. In the case of the types of simple systems discussed above, however, manufacturers needed a simpler, more cost-effective solution.
The Spansion FMcolor solution allows addition of colored HMI functionality/TFT display control into existing designs without the need for a dedicated graphics controller. The kits include an MCU as well as software components such as a matched TFT direct driver and a TFT wizard designed to ease the creation of simple graphical user interfaces (GUIs). Available with Spansion’s FM3 or FM4 MCUs, the solution controls both application and display. Because it is based on an ARM-Cortex CPU, the solution is versatile and scalable, offering an easy upgrade of existing applications to a colored display with minimal cost and effort. The developer simply needs to choose the appropriate MCU from Spansion’s scalable FM family and connect it to the display’s TFT; the FMcolor software takes care of controlling it. By simplifying the process, the FMcolor enables development teams to test and evaluate different approaches before committing to building a custom hardware solution.
Inside the box
With limited engineering hours and the pressure to deliver, embedded developers need to focus on their product’s unique value proposition, not on figuring out how to make a display present certain colors and shapes. The FMcolor development kits are available with either FM3 or FM4 MCUs based on the ARM Cortex-M3/4 family (see figure 1). The FM3 can be used for universal applications. FM4 offers additional DSP features and floating point unit (FPU) for performance hungry applications.
The box includes everything necessary to get started:
- a soldered MCU
- external flash memory
- external RAM capacitive touch buttons using the FMtouch solution and communication interfaces for USB, CAN, and Ethernet
- an on board debugger (CMSIS DAP)
- a standard debug connector
- a TFT display for immediate start
- the FMcolor software pack
Depending on the application, the resolution of the TFT display, and the color depth, the FMcolor solution presents three different means to connect a TFT display to an FM3 or FM4 MCU, either with or without external RAM. For example, a 320 x 240 pixel display with 8-bit color depth needs a minimum of 96 Kbyte RAM and can therefore be handled without the need to add external RAM. A 16-bit color display with a resolution of up to 480 x 272 does need external SRAM (8-bit or 16-bit external bus supported).
The firmware library part of the FMcolor solution consists of the following main modules (see figure 3):
– The TFTdriver module generates the timing signals to control the TFT display and handles data flow from RAM to TFT automatically. In order to avoid any flickers or artifacts, the driver synchronizes the update of the TFT content with the display timing. The TFT driver also includes simple graphic drawing routines, such as lines, rectangles or circles.
– The TFTobjects module provides predefined objects for HMIs such as simple buttons, checkboxes, text, and progress bars. It also includes control routines for user interaction via normal buttons, USB mouse, keyboard or touchscreen.
– The TFTUART module turns the TFT into a terminal window that can be handled like an internal UART. This feature can be helpful not only during development but also in the application, e.g. to show internal information to a service technician (hidden service console).
The PC-based TFT wizard tool allows creation of simple scenes using the objects defined in TFTobject and enables simple animations based on animated GIF files that can be imported and converted for use in the embedded system. TFT Wizard outputs C files suitable for use directly with the target system (see figure 4).
The starter kit comes pre-programmed; unbox it, connect the TFT display and a 9V power supply, and the software will start up (see figure 5). It can be used to quickly check functions and all peripherals.
The FMcolor solution targets applications that require cost-effective color TFT HMIs. For higher-end graphics performance, Spansion also offers microcontrollers with dedicated graphics hardware support including sophisticated layering, blending, and 2D/3D rendering functions for more dynamic HMIs or higher screen resolution and functionality.
Embedded designers face constant pressure to produce better products faster and more economically. The FMcolor development kit allows them to run the application and the simple color HMI from the same standard microcontroller. Perhaps just as important, development teams can use the kit to test out a design right out-of-the-box, allowing them to use only investigate different product approaches. Target applications range from vending machines and integrated coffee makers to diverse industrial equipment for which user experience is improved by upgrading the HMI to a color TFT display. Try and FMcolor development kit and see where the solution takes you.
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