![]() We used the same tantalum capacitor that we used for the PIC internal regulator. IC2 requires a 0.1uF bypass capacitor (C6) on the supply side, and a 10uF capacitor (C13) on the output. We recommend against using a ground fill under the connector without a solder mask.Ī 3.3volt supply, provided by an LD1117S33 (IC2), powers the PIC, microSD card, LCD logic, and LCD display. We prototyped an LCD carrier board prior to sending the final design for manufacture. We used sticky-tack to attach the LCD temporarily. Don’t depend on the connector to hold the LCD in place, use tape to hold it down. We fudged it by decreasing the pad size to get more space between. SparkFun has a PCB footprint for this part in their Eagle parts library, but the spacing between the pads is smaller than Olimex or BatchPCB will manufacture. The small connector is easy to solder on a professional board with a solder mask, but buy several as insurance. The ferrite bead type isn’t important, we used one left over from our tiny web server project. This even worked on a dirty home-etched prototype. We used a ferrite bead (L1) and 0.1uF capacitor (C5) to filter the supply, and haven’t experienced any problems. Many report noise in the display if this voltage isn’t clean. The LCD has a separate input for the 3.3volt display supply. The LED backlight requires a separate 7volt supply, and appears to have an internal current limiter because example designs don’t use external resistors. The LCD logic runs at 3.3volts and requires a decoupling capacitor (C4). This project is designed around SparkFun’s $20 color LCD panel. An LED indicates microSD read activity, but its also useful for general debugging (LED1, R2). ![]() The microSD card requires a bypass capacitor between the power pin and ground (C3). We tested several microSD card holders, and settled on one from SparkFun Electronics. ![]() MicroSD cards are completely compatible with regular SD cards, microSD cards can be used in an SD card reader/writer with an adapter. Buttons connected to the programming header could be used to set the time. The RTCC could be used as part of a function that superimposes the current time on the screen. These parts are optional, the initial firmware doesn’t use them. Read more about this chip in our PIC24F introduction.Ī 32.768kHz crystal (Q1) and two 27pF capacitors (C10,11) provide an oscillator for the real-time clock calendar (RTCC). R1 is a pull-up resistor for the MCLR function on pin 1. The chip is programmed through a five pin header, SV1. The internal 2.5volt regulator requires a 10uF tantalum capacitor (C12). Each power pin has a 0.1uF bypass capacitor to ground (C1,2). We really like this chip because the peripheral pin select feature lets us put important features on the pins we want this gives a smaller, simpler, more compact PCB. We used a Microchip PIC24FJ64GA002 28pin SOIC microcontroller (IC1) in this project. ![]() All the files for this project are included in the project archive linked at the end of the article. The circuit and PCB are designed using the freeware version of Cadsoft Eagle. A configuration file on the SD card defines the delay between images.Ĭlick for a full size schematic image (PNG). The PIC processes the image data and writes it to a color LCD over a unidirectional, 9bit SPI-like bus. A PIC microcontroller reads the images over a three wire SPI bus. The bitmap images are stored on common, PC-readable microSD cards. Our frame has a 12bit color LCD, gigabytes of storage on common, FAT-formatted microSD cards, and you can build it at home. We set out to build a 100% DIY, scratch-built digital picture frame. Most are old laptops with crafty case reconfigurations that fit a photo frame profile. There are a ton of digital picture frame tutorials out there.
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