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MP3...WAV...MIDI...FLAC...OGG... and many more Music Player by Bao Smith Got some music stored on your SD Card? Here’s an Arduino-based player that handles most common formats. It’s cheap, easy-to-build and it will even record as well. Build it . . . and be amazed! T his project uses an Arduino “MP3 shield” described in greater detail on page 72 of this issue. This delivers audio to a 3.5mm stereo jack which can be plugged directly into earphones/ headphones or to an audio amplifier to power larger speakers. For recording, it has an on-board electret microphone along with a mono 3.5mm jack socket, which allows an external microphone to be used. All the audio decoding/encoding and playback/recording functions are handled by the VS1053 IC on this shield. For more information on that IC, see the separate article on the shield. As well as playing back the compressed formats listed in the introduction, this IC is also capable of playing back General MIDI files and also uncompressed WAV files. It's an impressive chip, with quite a few extra feasiliconchip.com.au tures that we aren’t using in this project, such as digital tone controls. And of course, you can modify the software to take advantage of those features if you want to. While this device is capable of playing back a number of formats, most constructors would use it to play back either MP3 or AAC files, which are the de-facto standard formats for digitally compressed audio. Pretty much any music player should play back these formats. Until recently, MP3 was patented and so required licensed software for decoding. But that patent (held by the German firm Fraunhofer IIS) expired on the 23rd of April this year, so it is now an open format. Because it was patented, the similar open-source Ogg Vorbis standard was established. And more recently, AAC was developed, aimed mainly at providing either higher audio quality than MP3 at the same file size, or (in the case of AAC+) reasonable quality with a much smaller file size (bit rate). We’ve chosen to use the VS1053based Arduino shield because it is low cost, can play back all these file types and has a decent on-board DAC which is able to power nominally 30W loads such as many headphones and earphones; the minimum nominal load impedance it can handle is 16W. Construction Building this project is quite simple, with most of the connections made either by plugging a shield directly into the Arduino board or by connecting an external module to that same board using one of 12 short jumper wires. These are fitted with a male DuPont connector at one end and a female at the other. The first step is to slot the MP3 July 2017  77 Fig.1: wiring diagram for the Arduino Music Player project. The MP3 player shield should just slot in one-to-one with the Arduino Uno. The LCD screen with serial I2C can either go into Analog pins 4 & 5, or the SCL & SDA pins on the Uno as they are wired in parallel. You might find that your keypad has a slightly different layout, so it’s best to check with an ohmmeter what pin combinations correspond to which key. shield into the Arduino Uno (or equivalent), with the power connections matching up and the SD card slot on top of the USB connector. While you can upload the software at this point and start experimenting, with control via the USB serial monitor in the Arduino IDE, we will describe the remaining assembly steps first. The next job is to get the serial LCD screen running. We used a 16x4 screen but it will also work with a 20x4 alphanumeric display, however, you will need to modify one line in the software and the whole screen will not be utilised by default. The software could 78  Silicon Chip also be modified to work with a smaller 16x2 screen, if you wish. Refer to Jim Rowe's El Cheapo Modules series article titled “part 5: LCD modules with I2C” in the March 2017 issue for details on how these I2C LCD modules work. If you haven’t already fitted the I2C module to the LCD, generally it’s just soldered on the back, with a 1:1 correspondence between its pins and those on the main LCD board. We used a slightly unusual LCD module that we have on hand with a 20-pin connector, with pins 19 & 20 used for the back-light anode and cathode connections, compared to a more typical display which has these connections on pins 15 and 16. So you may notice on the photos that we soldered wire links between pins 15 and 19, and 16 and 20 to make the backlight work. Once you have the I2C module soldered to the LCD, the four I2C/power supply wires are easily connected to the MP3 shield (already connected to the Arduino board below), as shown in Fig.1. The I2C module normally has male pin headers while the Arduino shield has female sockets on top, hence we have specified male/female jumper leads to make these connections. Note that our software assumes the I2C module uses an address of 0x3F; some I2C modules use a different address (eg, if it uses a PCF8574T [0x27] rather than the PCF8574AT). So we suggest you check the supplied documentation and if necessary, change the LCD address in the software before uploading it. The final set of connections to be made are between the 4x4 keypad and MP3 shield as shown in Fig.1. We’re using a standard switch matrix type of keypad which is commonly available. If your keypad doesn’t have any pin siliconchip.com.au headers but rather has a series of pads with holes on its PCB, you will need to solder a male pin header onto it before proceeding (straight or right angle). The 4x4 keypad uses eight connections, four for the rows and four for the columns. After deducting the pins used by the “MP3 shield” and LCD, we’re left with ten free pins on the Arduino module and only a few of these are digital pins. Luckily, analog pins can also be configured as digital I/Os, so wire up the keypad as shown in Fig.1. Note that your keypad may use different row and column connections to ours but you can easily check this by setting a DMM in continuity mode, connecting it across each pair of pins and pressing each key on the keypad. You should quickly be able to determine which pins connect to the rows and columns. Note that after plugging in the keypad, the only pin remaining to connect anything else to your board is digital pin D1. If you do need to add other devices, consider using I2C devices which can be simply wired up in parallel with the LCD as long as they do not use the same I2C address. Software operation We won’t go into much detail regarding how the software works here; you can download and examine the code if you want to see how it works, or make any changes. However, it can be helpful to know how audio data is piped to the VS1053. The VS1053 has a 2048-byte buffer which can receive up to 32 bytes of data at a time. The data is sent via an SPI serial bus when the DREQ pin is high (this pin also indicates the chip is ready to receive a command over the SCI interface). Data can be sent either most-significant byte first (SM_SDIORD [0x9] set to 0) or least-significant byte first (SM_SDIORD set to 1) format; the SM_MODE register address is 0x4800 and this is configured over the SCI interface. The software requires four libraries to function, with one of them requiring minor changes to the code. The libraries required are SdFat, SFEMP3Shield (https://github.com/ madsci1016/Sparkfun-MP3-PlayerShield-Arduino-Library), LiquidCrystalI2C (https://github.com/fdebrabander/Arduino-LiquidCrystal-I2Clibrary) and Keypad (http://playground. arduino.cc/Code/Keypad#Download). It's important to mention that the version of SdFat we are using will only open files that use the old DOS 8.3 file naming convention (8 characters for name, 3 for extension). Files with names that do not match this format will not display properly and may cause other problems. The reason for this restriction is to save on memory. The software could be modified to support long file names but given that the basic Arduino module only has 32KB of flash and 2KB of RAM, and our software pretty much fills this, you would need a more powerful Arduino board to use the modified software (eg, one with an ATmega2560 chip rather than ATmega328). The software is capable of uploading various patches or “plugins” to the VS1053b chip. These can fix bugs in its firmware or add extra capabilities. They are stored in “little-endian” binary format on the microSD card, with a file extension of “.053”. These files can be created from .plg plugin files downloaded from VLSI's website (www.vlsi.fi/en/support/software/vs10xxpatches.html), using a conversion tool that comes with the SFEMP3Player library called "vs_plg_ to_bin.pl". Note that you might have trouble running the above Perl script if your version of Perl is lower than 5.10.0. As on line 59, a parameter for the pack() function makes use of the “<” modifier to force the data to be stored in little-endian format. You remove this modifier if you know your CPU architecture will only deal with data in little-endian format, or alternatively, you can set SM_SDIORD to 0 when sending the plugin data. The reason for converting them is to save storage space and speed up loading them into the VS1053b IC; even when converted to binary form, they can be quite large. The SFEMP3 library supplies some plugin files along with the software, already having been converted to this format. Their uses are described below. Installing the software The Arduino Music Player is easy to build, consisting of just four modules which plug together; either directly or via jumper leads. siliconchip.com.au If you don’t already have the Arduino integrated development environment (IDE) on your PC, download it and install it now. It’s available for free, from www.arduino.cc/en/Main/ Software We used version 1.6.12; SdFat requires version 1.6 or higher of the Arduino IDE to function, but it would be possible to convert it to function on earlier versions. Make sure all four libraries mentioned above have been installed or you will not be able to compile the July 2017  79 software. Minor changes were made to the SFEMP3Shield software to expose some internal functions required by our sketch. This modified version of the library will be included in the download package on the Silicon Chip website, along with the actual sketch itself. Once you have the library ZIP files, you can install them in the Arduino IDE via the Sketch→Include Library→Add .ZIP Library menu option. You will also need the two VS1053b plugin/patch files named "patches.053" and "oggenc.053", also included in that download package. When the sketch runs, it looks for these files in the root directory of the microSD card, loads them into its memory and then uploads them to the VS1053b IC. The first patch file is an update to the chip’s firmware that fixes some bugs and also adds extra capabilities. Some of the bug fixes are required to play certain audio files that would otherwise return errors. The second is the code which allows the chip to record in Ogg Vorbis format. Without these files, the unit will not function properly. Once you’ve placed these files on the microSD card, along with whatever audio files you want to play back, plug it into the socket on the shield. Note that the SD card should be formatted with either FAT16 or FAT32 file systems to work with the SdFat library. Having ensured the libraries are installed, open up the sketch (called “VS1053_example.ino”) in the Arduino IDE and plug the Arduino into your PC using an appropriate USB cable. We assume you know how to select the appropriate USB serial port in the Arduino IDE; if you’re unsure, we’ve described this procedure before, for example, in the Arduino-based Digital LC Meter article, published in the June 2017 issue (on pages 35 and 36). You can now use the Sketch→Upload menu item to load the software into the Arduino. Using the module When the software has been loaded and the module is up and running, you should notice that the display has lit up and menu should be shown. This menu can be navigated using the keypad with the keys labelled 2/8 corresponding to up/down, 4/6 to left/right, 5 being “enter” (selecting the menu 80  Silicon Chip Parts List 1 Arduino Uno or equivalent with ATmega328 chip (Jaycar Cat XC4410) 1 Geeetech Arduino MP3 Player Shield (Silicon Chip online shop Cat SC4315) 1 20x4 or 16x4 LCD screen with I2C backpack module (Silicon Chip online shop Cat SC4203) 1 4x4 matrix keypad (other sizes will also work with software changes) 1 8-pin header, 2.54mm pitch, straight or right angle (to suit keypad) 12 male-female DuPont jumper leads (Jaycar Cat WC6028) 1 USB Type-A to Type-B “printer” cable (to suit Arduino module) 1 microSD card formatted in FAT16/32, capacity to suit application 1 7-12V DC plugpack with 2.1mm inner diameter plug (optional, for standalone use) entry that the cursor is currently on) and * functions as a general “back” key in all menus. The menu items that are available on the main menu, by default, are: 0. plays all music files available on the SD card. Pressing 4/6 will go to the previous/next song, “A” will restart the song from the beginning, 5 will pause/unpause, 1/3 will decrease/increase playback speed and 7/9 will increase/decrease playback volume. During playback, it will display the file name, current time and a VU meter signal level for the left and right channel. Playback can be stopped by pressing the “*” key and it will stop automatically after the last file has been played. Note that there is a limit of 50 files due to memory constraints (2 bytes are required per file). The software could be modified to remove this limitation but then it would not be possible to step backwards, to the previous file; you could only skip forwards through the list. 1. lets you select a file to play. 2. record to an .ogg file named recordXX.ogg, where XX starts at 00 and is incremented per recording. 3. toggles between mono and stereo output 4. resets the VS1053 chip to its default settings 5. produces a test sinewave from the outputs 6. turns on/off the differential output mode 7. put the VS1053 IC in low-power sleep mode 8. exit sleep mode Recording uses the on-board electret microphone. If you want to use the line input instead, you need to add a line at the top of the sketch which reads “#define USE_LINEIN" without quotation marks. The audio is recorded in Ogg Vorbis format at approximately 128kb/s and saved as an “.ogg” file. In addition to the keypad/LCD interface described above, the software can be controlled from your PC using the serial monitor. You simply read the menu options that are displayed on the serial monitor and choose one by pressing the associated key on your keyboard. This interface has additional options which can be used for debugging. Making simple changes to the code Experienced programmers should have no problems changing the software to suit their needs but even relative beginners can make some changes, as described below. A constant called MAX_INDEX defines how many files the software can handle on the microSD card. Changing this will also affect how much SRAM is used. If you increase it too much, there won’t be enough free memory for the software stack and it will no longer work properly. Each additional entry will take another 2 bytes of SRAM. The definitions LINE1, LINE2, LINE3 and LINE4 are the addresses of each line of the display on your LCD module. The module we used has the first line at address 0 hex, the second line at 40 hex, the third line at 14 hex and the fourth line at 54 hex. This is pretty standard and most displays should use the same addresses, but if yours is only displaying the first line correctly, you may need to change these. siliconchip.com.au Silicon Chip Binders REAL VALUE AT $16.95 * PLUS P & P Here you can see the initial display when the unit is first powered up after loading the software, showing part of the main menu. The underline indicates which menu item will be selected when you press enter (5 on the keypad). Our I2C LCD uses the PCF8574AT IC and so the software is set up from an I2C address of 3F hex. If your LCD interface has a PCF8574T, change the line which reads: LiquidCrystal_I2C lcd(0x3F, LCD_COLS, LCD_ROWS); to: LiquidCrystal_I2C lcd(0x27, LCD_COLS, LCD_ROWS); Regarding the changes made in the SFEMP3 library for this project, they can be summarised as the following: 1) playTrack(uint8_t) was changed to playTrack(uint16_t) to allow more than 255 files on the same card (using the naming scheme trackX.mp3, where X is a number between 0-999). 2) isFnMusic(char *) was changed to also check for Ogg Vorbis files. 3) the following functions in the SFEMP3 class were changed from “private” to “public” to allow the sketch more control over the VS1053b IC: void getTrackInfo(uint8_t, char*, uint8_t); // Gets MP3 ID3 metadata (force appends a null-byte) static void Mp3WriteRegister(uint8_t, uint16_t); // Write 16-bits to a given register static uint16_t Mp3ReadRegister (uint8_t); // read from a given register siliconchip.com.au uint8_t VSLoadUserCode(char*); // Load a .53 format plugin Additional uses As noted earlier, the SFEMP3Player library has treble and bass controls, however, our software does not use these functions. If readers want to work on the software, this would be one area to start. Another improvement that could be made is to take advantage of the library’s functions for reading header information (eg, ID3 tags), and display it on the LCD during playback. The chip itself is surprisingly powerful, handling all the decoding/encoding itself in real time. It can also be used as a graphic equaliser and MIDI synthesiser. VLSI also offer software to use the chip as a FIR (finite infinite response) filter, in combination with the free GNU Octave software. This can be found under VSIDE DSP Library: www.vlsi.fi/en/support/software/ vs10xxapplications.html Using it is outside the scope of this article, though. The VS1503 manufacturer's website can be found at www.vlsi.fi/en There you can find other example programs (not for Arduino) along with a list of patch files (www.vlsi.fi/en/support/ software/vs10xxpatches.html) and bonus functionality that can be loaded SC into the chip. 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