Programmeerbare audio-spelers

De solid-state audio-spelers leveren hoge-kwaliteit audio. Deze spelers hebben interfaces naar externe apparaten, sensoren (vandaalbestendige) schakelaars, LEDs en relais. Door deze flexibiliteit in samenhang met het temperatuurbereik en het solid-state ontwerp, maken de audio-spelers zeer geschikt voor toepassing in kiosks, maquettes, exhibitie-centrums, spel-consoles en andere.

De speler is, zoals al genoemd, "programmeerbaar" door de eindgebruiker, door middel van een scripttaal. Daardoor is de audio-speler gemakkelijk "passend" te maken voor een specifieke toepassing.

Model H0420

Model H0420 ondersteunt alleen MP3-tracks (op elke bitrate). De speler leest de audio-tracks van een CompactFlash kaart. De audio uitgang is lijn-niveau, via twee tulp-pluggen. Beschikbare interfaces zijn:

• 16 ingangen (met dender-filter), voor schakelaars
• 16 digitale I/O pinnen, één analoge pin (uitgang)
• RS232
• via een extensie-print kan de H0420 aan een lokaal netwerk worden gekoppeld

(meer informatie...)

Model H0430 (Starling serie)

Model H0430 ondersteunt MP3, ongecomprimeerd WAVE en Ogg Vorbis. Het gebruikt een micro-SD kaart voor opslag (en de audio-content). De H0430 heeft een I/O-connector die flexibele aansluiting mogelijk maakt, zonder gereedschap te vereisen. Een 2 × 15 Watt klasse D versterker laat u direct passieve luidsprekers aansluiten. Als alternatief bied de H0430 een 3,5 mm jack-plug voor een koptelefoon of line-out signaal. Beschikbare interfaces zijn:

• USB interface
• 16 digitale I/O pinnen, één analoge pin (uitgang)
• RS232 (tweevoudig)
• SPI, met dubbele "slave select" pinnen
• temperatuur-sensor
• klok met backup-batterij

(meer informatie...)

Model H0440 (Starling serie)

Model H0440 ondersteunt MP3, ongecomprimeerd WAVE en Ogg Vorbis. Het gebruikt een SD/MMC kaart voor opslag (en de audio-content). De H0440 heeft een dubbele audio-decoder, waarmee het twee tracks tegelijkertijd kan afspelen. De audio van beschikbaar op een pin-header voor elke decoder apart, en het gemixte signaal staat op de tulp-pluggen (lijn-niveau). Beschikbare interfaces zijn:

• netwerk (100 Mbit/s, met auto-negotiation)
• 8 digitale I/O pinnen, één analoge pin (uitgang)
• RS232 (tweevoudig)
• SPI, met dubbele "slave select" pinnen
• temperatuur-sensor
• klok met backup-batterij

(meer informatie...)

Extra documentatie, voorbeelden en uitbreidingen zijn beschikbaar in de Engelse taal:

Programming the MP3 controller/player: getting started

2015-03-07
This article steps through the creation of a very simple program, from the installation and configuration of the tools to the evaluation of the result. It refers to model H0420, but most concepts also apply to the Starling players.

Playing tracks sequentially

2015-03-07
A sequel to the above tutorial, in which we develop a script that plays MP3 tracks one after another (and in a random order).
    Most recent update: This update of the article makes switching from one track to the next track even faster, by creating "resource ids". The discussion on track separation has been moved, with many enhancements, to a separate application note.

Track and artist separation

2015-03-07
When selecting the tracks to play at random, you will often want a form of track separation or, better yet, artist separation, so that the same track (or one of the same artist) does not play too quickly again. This article discusses how to implement track separation and artist separation.

Synchronizing activities with music

2018-03-03
An ID3 tag in an MP3 track may optionally contain text or commands with time stamps. These time stamps allow the text or the commands to be synchronized with the music. The H0420 MP3 controller supports this extension, and the article gives a complete example implementation.

Gapless looping MP3 tracks

2020-10-23
Due to the file format and the algorithm of MP3 tracks, creating a loop without a gap or click is a little involved, especially when using a hardware player. The H0420 MP3 controller and the Starling audio controller can play gapless MP3 audio loops, provided that special software has processed the MP3 track.
    Example tracks & processing software are available from this site, as well as a detailed presentation of how it works.
    Most recent update: The software was improved with better interpolation in the resampling phase, a GUI "wrapper" utility was added for ease of use.

A remote-controlled MP3 player

2019-04-29
Adding functionality to manipulate the H0420 MP3 controller with a common remote control only takes the IR-receiver chip and a pull-up resistor, plus a script that interprets the codes sent by the remote control. This article goes into details and provides a general purpose script for RC5 codes (other infrared protocols are supported by modifying the script).

Connecting a bar-code wand to the MP3 controller/player

2015-03-07
The H0420 MP3 controller supports a low-cost bar-code wand directly on its I/O pins (only a pull-up resistors sometimes needs to be added). This article descibes the connections and presents a script that decodes the "interleaved 2 of 5" bar-code symbology.

Synchronizing time with DCF77

2018-03-03
This article describes how to synchronize the internal real-time clock of the H0420 MP3 controller on the time signal emitted by the atom clock on the DCF77 transmitter.
    Most recent update: The article also discusses the MSF60 transmitter (in Great Britain) and protocol.

Encrypted MP3 tracks

2018-03-03
The H0420 MP3 controller and the H0440 audio player/controller are able to play encrypted MP3 tracks directly (without needing an intermediate decryption phase, and so without start-up delay). This article discusses the software and the operations necessary to create MP3 tracks with strong encryption (and how to play them back).

A MIDI to RS232 converter

2018-03-03
The MIDI protocol is a serial data communications protocol using on a "current loop" physical layer, and using a Baud rate of 31250 bps. This article shows the electronics needed to convert between current loop and the RS232 signal levels. The circuit can be connected directly to the RS232 port of the H0420 MP3 player. In the second part, the article covers the "software protocol" of MIDI and develops a simple script to send and receive MIDI commands.

Power-outputs for the programmable audio controller/player

2015-03-07
Both the programmable MP3 player model H0420 and the Starling audio player have digital I/O pins with TTL-level output. This note describes how you can get more power (and/or a higher output voltage) from the I/O pins.

LED current source

2015-03-07
Both the programmable MP3 player and the Starling audio player have digital I/O pins with TTL-level output, which can directly drive a single LED. This note describes a constant current source that you can use to drive more than one LED, at an equal brightness, controlled from just one I/O pin.

A voltage inverter circuit

2015-03-07
The programmable MP3 player model H0420 directly supports LCDs with a HD44780 controller and a positive LC-driving voltage. With the voltage inverter described here, you can also attach LCDs that need a negative LC-driving voltage.

H0420 Internals

2018-03-03
The internals of the H0420 are briefly touched upon in this on-line article. The notes cover both the hardware and the software ("firmware").

Interfacing the VS1053 and VS1063 to DACs and SRCs

2018-03-03
The VS1053 and VS1063 audio decoder chips from VLSI Solutions support I²S output (in addition to analogue audio output). However, the specific I²S format narrows your choice of DAC, SRC or DSP. The simple circuit presented in this application note converts the I²S format from the VS10x3 to 32Fs Right-Justified, which has much wider support by DAC, SRC and DSP chips.

The STA013 MP3 decoder

2018-03-03
This paper is a collection of hardware notes on the use of the STA013 MP3 decoder from STMicroelectronics. The paper also contains some notes on the MP3 file format.