MP3 Player with Automation Interface – MP3-445

The MP3-445 is a highly versatile, highly configurable MP3 player and automation interface with an onboard audio amplifier and extensive electrical input and output options. It can be everything from a doorbell, to the control center for a complex public multimedia display. It operates independently or using the built in serial interface, it can control other devices or be controlled by other devices, including computers.



  • Solid-state Compact Flash MP3 Player supporting MPEG2 Layer 3 Stereo decoding at all MPEG sampling frequencies and bit rates up to 256 kb/s including variable bit rate (VBR).
  • Operates in two stand alone modes (simple & enhanced), and a peripheral mode (interfaced to a remote computer or other device).
  • Line-level unbalanced/balanced-isolated stereo outputs.
  • On-board power amplifier capable of 2 x 25W stereo outputs with output AC/DC short-circuit protection.
  • 16 switch inputs with transient protection.
  • 2 opto-isolated inputs.
  • 16 outputs with 250mA continuous or 1.5A pulsed current per output.
  • Supports Compact Flash Cards type I and II with capacities up to 4GB.
  • Standard serial interface (RS-232) running at 9600 baud.
  • DIP Switch selectable level/edge triggered inputs and audio level adjustments.



Input power9VAC-12VAC @1A or 12VDC-16VDC @ 1A
Current consumption130mA typical during MP3 playback (without power amplifier), 80mA when idle
Storage mediumFAT16 formatted Compact Flash (CF) Cards Type I and II
Storage capacity4GB


Switch inputsActive low with transient protection. DIP Switch selectable triggering
Opto-isolator inputs3V to 12V DC
Outputs250mA continuous and 1.5A pulsed current per output


DecoderSTA013 single chip MPEG2 Layer 3 decoder supporting STEREO and
MONO channels and all MPEG 1 & 2 sampling frequencies and bit rates
Up to 256 kb/s including variable bit rate (VBR)
Frequency response20Hz to 20 kHz
DistortionTHD < 0.3% 2x10W/4ohm @ 14.4V, 1 kHz
THD < 10% 2x25W/4ohm @ 14.4V, 1kHz


Dimensions203mm (L) x 137mm (W). CF card exceeds longer edge by 12mm
Weight0.27 kg
Mounting4 holes dia 3.35mm spaced 190mm horizontally and 123mm vertically

Operating conditions

Operating Temperature0°C to 60°C
Storage Temperature-20°C to 70°C
Humidity5% to 80% RH non-condensing


 Simple Stand-alone Mode

Inputs14 edge-triggered or 7 level-triggered, non-triggerable switch inputs.
Opto-isolated inputs 1 and 2 mapped to switch inputs IN09 and IN10.
Either rising or falling edge transitions recognised based on DIP switch settings. See DIP Switch Settings.
Outputs14 high-current outputs. One-to-one correspondence between outputs and inputs.
Playback14 MP3 tracks. See MP3 Track Numbering. One-to-one correspondence between MP3 tracks and inputs.
Volume adjustmentSwitch inputs IN15 and IN16. Volume adjustment is done in real time and final value is written to EEPROM after track ends.

Enhanced Stand-alone & Peripheral mode

I/O16 unique inputs and outputs
Playback255 MP3 tracks. See MP3 Track Numbering.
Serial I/F4-pin header; 0-5V TTL levels; 9600 baud
CommandsRead inputs, change outputs, play/stop track, send configuration file/entry, change volume. See Peripheral Mode Commands & Responses
Configuration File255 rules supporting 16 Input Edges/Levels, 16 Outputs, 16 Timers, 16 Variables, multiple IF-THEN constructs. See MP3 Configuration File
Volume adjustmentSoftware controlled. 256 levels in steps of 1.5dB

Click here for Application Notes.
Click here for Wiring Information.



The MPC-494 is a small 50mm x 18mm board which piggybacks on to the serial port of the MP3-445 Compact Flash MP3 board. It controls I/O and MP3 playback based on rules in the user changeable configuration file stored in the Compact Flash.


The OPT-466 Opto-isolator board connects to any 4 of the 16 inputs of the MP3-445 to convert them into 4 opto-isolated inputs.
Click here for detailed specs on the OPT-466


RLY-312 Relay Board connects to 4 of the 16 outputs of the MP3-445 to convert them into 4 DPDT relay outputs, each capable of switching loads of 60W/125VA.
Click here for detailed specs on the RLY-312.