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Project by Gianni Pallotti These days most mobile phones can play audio files (in formats like MP3 and WAV) but sometimes you just want something simple to play some music or sounds. This circuit uses little other than a Micromite LCD BackPack and a DFPlayer Mini module, and it can play such files from a microSD card. Micromite-based MUSIC PLAYER S ome potential uses for this design include playing sounds or white noise to drown out a noisy environment (such as construction noise), or playing calming music before bedtime, which can benefit some children or those with insomnia or tinnitus. Depending on personal preferences, options like coloured noise, soothing music or natural sounds such as running water, animal sounds or rain can help you to relax and fall asleep easily. A consistent sound, like running water or waves crashing, can help to mask background noises without being intrusive. I have succumbed to tinnitus (commonly known as ringing in the ears) and, after trying some possible solutions, I have found the best one is listening to soft sounds during the silent part of the day and night. Although there are various ways to listen to such sounds, including apps, websites and dedicated devices, I liked the idea of building my own player. I am using it to play the calming patter of rain on a window, soft rustling leaves, birds chirping, plus wind and ocean wave noises. They also help to focus our attention outward rather than on our own anxiety or obsessive thoughts. This project could also function as a digital MP3 music player, capable of storing and playing plenty of songs. The DFPlayer Mini MP3 player module (data sheet: siliconchip.au/ link/ac83) used in this design was described in detail in the article titled “A stamp sized digital audio player” (December 2018; siliconchip. au/­Article/11341). I also used it in a previous design, the Slot Machine project (May 2022; siliconchip.au/ Article/15310). microcontroller and LCD, effectively turning it into an ‘audio BackPack’. For the first two options, most components used are obtainable from the Silicon Chip Online Shop, such as the Micromite LCD BackPack kit (see siliconchip.au/Shop/20/3321) and DFPlayer Mini (siliconchip.au/ Shop/7/4789). The only other required Fig.1: very little needs to be added to a Micromite LCD BackPack to turn it into an audio player. The audio files are stored in MP3 format or similar on a microSD card plugged into the DFPlayer Mini module. Assembly options An enlarged view of the DFPlayer Mini’s underside. The module is shown at actual size in the lead photo. 78 Silicon Chip The circuit is quite basic, as shown in Fig.1. There are three ways to build the Music Player: 1. You can wire up the DFPlayer Mini module and other parts (there are just a few) to a Micromite LCD BackPack using jumper leads or by soldering wires. 2. You can build my small add-on board that hosts the DFPlayer Mini and other parts, and plugs into the LCD BackPack. 3. I have also designed a board that has everything onboard, including the Australia's electronics magazine siliconchip.com.au An empty cotton bud container is an inexpensive way to house the finished project. The add-on board for the Music Player. It’s a simple design due to most of the work being done by the Micromite BackPack. There is a single 1kW resistor on the underside. component is an adaptor for linking the DFPlayer to the BackPack. The optional PCB coded 01110251 (38.5 × 30.5mm) plugs into the BackPack and hosts the DFPlayer Mini plus a handful of other components, making both the construction and wiring easy. The optional all-in-one board, which uses a 2.4-inch touchscreen rather than the 2.8-inch one used on the BackPack, is coded 01110252 and measures 87 × 52mm. Besides connecting the audio player module to the BackPack, both boards also facilitate connections to a loudspeaker and the input power supply. The whole assembly will easily fit inside a small container measuring 110 × 80 × 55mm or so. I have found it very economical to use an empty cotton bud container for this. It costs just $2.99, and you get 200 cotton buds as a bonus! I painted the inside of the clear box to minimise any light from the LEDs on the DFPlayer Mini module showing through it, but you might like that effect. The cutouts required for the LCD panel, speaker, USB power input and on/off switch when using this container are shown in Fig.2. I used a 2.8-inch Micromite LCD BackPack V1 as it’s the simplest and cheapest of the BackPacks that use the 2.8-inch TFT touchscreen. You can use the V2 (with onboard USB interface and PWM backlight dimming) or the V3 (with even more features, although we don’t need any of them here). In the following description, I will assume you are going to use the V1 like I did. As there is no PWM option to reduce Fig.2: these are the cut-outs required in the specified 110 × 80 × 55mm box. You could use a larger box, but will need to adjust the hole positions. the LCD panel backlight on the V1 Micromite LCD BackPack, the unit can simply be placed face-down if you don’t want bright light from the screen. This will have the added advantage of better dispersion from the speaker hole in the rear of the case. If you use the larger all-in-one board, you don’t need to assemble a BackPack; it’s integrated into that design, as shown in the Fig.3 circuit. If you are using the separate BackPack, build the BackPack first, then assemble the add-on board as per Fig.4. 80 Silicon Chip It’s pretty straightforward. If building the all-in-one version, mount the components as per Fig.5 now. For the all-in-one version, either fit the 13W resistor and omit Q1 & Q2 for fixed touchscreen backlight brightness, or omit the 13W resistor and fit Q1 & Q2 for PWM backlight brightness control. Importantly, if your touchscreen has yellow plastic on the 16-pin connectors, it will run at full brightness regardless of the value of the 13W resistor, unless you opt for PWM backlight control. Australia's electronics magazine Note that if you are using Micromite LCD BackPack V3, or the all-in-one PCB with PWM backlight brightness control, by default, the backlight will be driven with a 50% duty cycle. It’s possible to have touchscreen controls to adjust the brightness, but they are not part of the supplied software. So if you want such controls, you will need to add them. Once the board(s) have been assembled, wire them up and mount the components in the case as shown in Fig.6 (overleaf). This shows the wiring siliconchip.com.au Fig.3: this is the simplified circuit of the larger all-in-one PCB that uses the 2.4-inch touchscreen. The other difference is the BUSY signal from the DFPlayer Mini module goes to pin 6 of IC1 instead of pin 24. Fig.4: it’s easy to build the add-on board; it basically exists just to connect the DFPlayer Mini module (via two header sockets) to the BackPack and loudspeaker. Fig.5: this board has all parts onboard so doesn’t require the BackPack, although it’s sized for the 2.4-inch touchscreen rather than 2.8-inch (they have the same pixel resolution). The screen plugs into CON4 & CON5 and mounts on the three tapped spacers. for the add-on board version. Note that the speaker wiring polarity is unimportant. Keep in mind that, if you use a USB-C socket like I did, and it doesn’t have any onboard resistors (most don’t), it isn’t guaranteed to work if you use a Type-C to Type-C cable. It will work with Type-C to Type-A cables, though. If you’ve built the all-in-one version, the USB socket is onboard, so position it to be accessible through the hole in the case. There is no power switch in siliconchip.com.au this case; you unplug it to switch it off. The speaker wiring is the only external wiring required. Software Once the board(s) have been built, assuming the PIC32 chip is programmed with the Micromite firmware, you just need to load the BASIC code onto it. You can do this by using a USB/Serial adaptor or, if your BackPack has a USB socket, via that socket. Refer to the Micromite and BackPack articles for detailed instructions on Australia's electronics magazine doing this. The basic procedure is as follows. You will need a serial terminal program, such as TeraTerm on the Windows operating systems. The AUTOSAVE command is probably the simplest way to load the BASIC code. You will also need to configure the Micromite OPTIONs to enable the LCD panel and touch sensor, then calibrate the touch sensor. If you haven’t used a Micromite processor before, Geoff Graham’s Micromite webpage includes all the April 2026  81 information you might need on the Micromite (see https://geoffg.net/ micromite.html). The Micromite manual, which you can download from that page, includes instructions for configuring LCD touch panels. The BASIC files list the OPTIONs in comments near the start. There are two different files. “Sound Player.bas” is used with the Micromite BackPack PCB, while “Sound Player2.bas” is used with the All-In-One PCB. Parts List – Micromite-based Audio Player Common to all versions 1 plastic box, 110 × 80 × 55mm 1 DFPlayer Mini audio player module [Silicon Chip SC4789] 1 4W 3W miniature loudspeaker [Adafruit 3351] 1 microSD card 1 2-pin right-angle female header socket, 2.54mm pitch 4 10G × 10mm self-tapping screws 4 M3 × 25mm panhead machine screws 4 M3 × 12mm tapped nylon spacers 4 M3 × 3mm untapped nylon spacers 2 M1.6 × 6mm machine screws and nuts 1 50cm length of twin medium-duty red & black cable Operating the Player Add-on PCB version The Micromite program is controlled through touch commands on the LCD screen. All-in-one version These include the following main buttons (see Screen 1): PLAY: start playing a track PAUSE: pause playback of the current track <PREV: play the previous track in the same folder NEXT>: play the following track in the same folder FOLD: change to the next available folder and play the first track −VOL: decrease the volume, from a maximum of 30 down to 0 +VOL: increase the volume, from a minimum of 0 up to 30 1 2.8-inch Micromite LCD BackPack programmed with MMBasic V5.05.05 [SC3321] 1 single-sided PCB coded 01110251, 38.5 × 30.5mm 1 SPST panel-mount switch (toggle or slide) 1 1kW SMD resistor, M2012/0805 size Connectors 1 panel-mount USB socket with breakout board 1 14-pin female header socket, 2.54mm pitch 1 2-pin right-angle header, 2.54mm pitch 1 double-sided PCB coded 01110252, 87 × 52mm 1 2.4-inch ILI9341-based LCD touchscreen module 1 PIC32MX170F256B-50I/SP microcontroller, DIP-28, MMBasic V5.05.05 (IC1) 1 28-pin DIL IC socket (optional; for IC1) 1 MCP1703AT-3302E/MB 3.3V LDO voltage regulator, SOT-89 (REG1) 1 2N7002 N-channel Mosfet, SOT-23 (Q1) 1 AO3401(A) P-channel Mosfet, SOT-23 (Q2) 4 10µF 50V X5R SMD ceramic capacitors, M3216/1206 size 2 100nF 50V X7R SMD ceramic capacitors, M3216/1206 size 1 10kW SMD resistor, M2012/0805 size 3 1kW SMD resistors, M2012/0805 size 1 13W SMD resistor, M2012/0805 size (optional; fixed backlighting; omit Q1 & Q2) Connectors 1 PCB-mounting 4-pin USB mini Type-B miniature socket (CON1) 1 4-pin female header socket, 2.54mm pitch (CON4) 1 14-pin female header socket, 2.54mm pitch (CON5) Screen 1: the default screen of the Audio Player in use. The round buttons provide the following options: PLAY ONCE: play the selected track once only REPLAY: continuous looping of the selected track 2HRS: stop playback after two hours SAVE: saves the current folder, track selection, play mode and volume The SAVE button changes to yellow each time a setting is changed, then reverts to white when the button is touched, confirming that the new settings have been saved. This is a reminder to save the changes. At startup, the stored data (if saved) is loaded and the MP3 is set accordingly. Otherwise, it uses the defaults: volume = 15, folder #1, track #1, no repeat (play once). The list of folders is hard-coded in the Micromite MMBasic program. For example, by default the line is: DIM FolderName(4) As String = (“1-Nature”, ”2-Rain”,”3-Water”, ”4-Wind”,”5-Sounds”) 82 Silicon Chip Australia's electronics magazine siliconchip.com.au The finished Music Player fits neatly in the painted plastic box that the cotton buds came in. Only the red (+) and black (-) wires need to be connected. This is the 3W speaker I used. It works well and I recommend it, but there are plenty of other options. The reason it’s (4) instead of (5) is that there is an index zero, so with a maximum index of 4, up to five strings can be stored. You can change that number, but make sure it’s always one less than the number of folders listed. Each folder can contain as many as 3000 tracks, assuming the SD card has sufficient capacity. If the next folder or previous/next track is not found, the program will revert to the first folder saved on the microSD card, or to the first track in the pre-selected folder. The name of the folder and the track number within the selected folder will show on the LCD panel. The volume setting is shown as a bargraph and as a number next to the graph. Micromite pins 9 & 10 (COM2) are used for the 9600 baud bidirectional serial communications port with the DFPlayer Mini module. The commands sent to the module have been reduced to only the strict requirements, each consisting of three strings: Initiate$ + Function$ + End$. The Function$ string is the main command SC component. Fig.6: how to wire up the add-on module to the BackPack (V1 shown here), speaker, switch and power socket. The wiring for the full board shown in Fig.5 is much simpler, as only the speaker needs to be connected. siliconchip.com.au Australia's electronics magazine April 2026  83