Beocreate – Hardware documentation
Beocreate – Hardware documentation
Connectors
| 1 | External power supply 12-20V, barrel jack 5.5×2.1mm (outer pin -) |
| 2 | Toslink Digital Input to connect external sources (e.g. Chromecast audio) |
| 3 | Toslink Digital Audio output (e.g. to daisy-chain multiple boards) |
| 4 | External power supply 12-20V, screw terminal. Use 1 or 4, but not both! |
| 5 | Speaker terminals (60W channels on the bottom, 30W channels on the top) |
Jumpers
Board release 1.x
Board release 2.x
| 1 | Selfboot – With this jumper set, the DSP always loads it’s program from the onboard program memory. Always keep this on, except you want to program the DSP with your own tools. This is not uses anymore on board release 2.x |
| 2 | GPIO connector – gives you access to some of the Raspberry Pi GPIOs and some of the DSP GPIOs. Documentation |
| 3 | 48/96/192kHz jumper. By default the internal sample rate of the DSP is 48kHz. This allows the maximum computing power. If you want to design your own DSP program that runs at higher sample rates, this jumper has to be set. This is only for very advanced users. Changing the sample rate of the DSP will require a lot of changes in the provides sample project! |
| 4 | MUTE – mutes the amplifier output. We recommend to remove this. You can also control the MUTE function from the Raspberry Pi or from a DSP program. |
| 5 | Output voltage limiter – This limits the output voltage of the 2 30W channels. This is especially recommended if you experiment with DSP programs and you’re not yet sure if everything work well. This protects your speakers from getting damaged by a DSP program that outputs a full volume signal. If you’re using our DSP programs, remove this jumper. This jumper has been removed on board release 2.x |
| 6 | Power switch jumper. If the power switch feature (see 8) isn’t used, at least one of the jumpers need to be set. Setting this jumper bypasses the VIN/VSW switch |
| 7 | Additional GPIOs: top: RPI I2C SCL/RPI I2C SDA bottom: RPI GPIO15/14 |
| 8 | Power switch: You can connect a switch between VIN and VSW. This turns on/off the power of the whole system: Pi and Beocreate. |
DSP Channels
The DSP used on the Beocreate 4 channel amplifier can handle up to 48 input and output channels. If you design your own DSP programs, it is important to know which channels are used on our board. The following picture shows you the mapping.
Note that both the Raspberry Pi input and the SPDIF input can’t be connected directly to the DSP core, but via one of the asynchrounously sample rate converters (ASRC) that are integrated. The reason for this is the following: The DSP core always runs at a fixed sample rate (our profiles use 48kHz, but you can also use sample rates up to 192kHz), while both the SPDIF input and the Raspberry Pi audio input can run at different sample rates. Therefore, there need to be converted to the sample rate of the DSP core.
Well, doesn’t have this a negative impact on the sound quality? While simple sample rate conversions can have a negative impact on sound quality, the ASRC on the DSP performs very well. It provides a signal-to-noise ratio of 120dB. Therefore there is no audible impact on the sound quality.