AN1387 Using PIC32 MCUs to Develop Low-Cost Controllerless (LCC) Graphics Solutions Basic Graphics Definitions Author: Adam Folts, Microchip Technology Inc. Pixel One dot of color data on a LCD. Refresh Rate Defined in Hertz (Hz), the rate at INTRODUCTION which the LCD panel frame is being redrawn per second. As the demand for Graphical Embedded Applications Resolution Defined in horizontal by vertical becomes more popular, so does the need for dimensions, the number of pixels a certain display developing cost effective solutions. Many companies panel contains. For example, a QVGA LCD panel that today offer solutions involving an additional internal or is 320x240 pixels has a horizontal pixel count of 320 external graphics controller as part of a system, which and a vertical pixel count of 240. may result in higher costs and more complicated designs. In most cases, for a simple embedded Graph- Pixel Clock (PCLK) LCD panels uses this signal to ical User Interface (GUI), these graphics controllers synchronize the sampling of incoming color data. The are not necessary, but a suitable solution may not be clock signal needs to be faster for higher resolutions so available. One solution that is becoming more popular that all pixels of a frame can be clocked. is to use a controllerless solution. This solution uses Frame Buffer Volatile memory where pixel color data microcontroller (MCU) peripherals to create a virtual is stored for the purposes of refreshing an LCD screen graphics controller for graphics rendering without of a certain resolution taking up large amounts of CPU time (in this solution Pixel Throughput Speed at which a pixel can be less than 5%). redrawn. The time to draw an entire frame would be The Low-Cost Controllerless Graphics PICtail Plus pixel throughput multiplied by the LCD screen Daughter Board (referred to as the LCC Graphics resolution. Board), was designed to showcase a technique offered Color Depth Defines how many possible colors a by Microchip that utilizes this low-cost controllerless pixel can be drawn. Commonly represented in bits per method and is designed to work with many existing pixel (BPP), a common color depth is 16 BPP, where the PIC32 starter kits. color data is represented in a 565 RGB color format. In This application note describes the LCC Graphics this format, 565 represents 5 red, 6 green, and 5 blue Board that enables the implementation of a low-cost color bits. controllerless graphic method using a PIC32 microcontroller. BOARD SETUP Figure 1 shows the setup for a PMP-configured LCC Graphics Board with a USB Starter Kit II, connected to a 480 x 272 LCD display. 2011 Microchip Technology Inc. DS01387A-page 1AN1387 DS01387A-page 2 2011 Microchip Technology Inc. FIGURE 1: LOW-COST CONTROLLERLESS (LCC) GRAPHICS BOARD SETUP