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Schematics

A project log for OggStreamer / LiveRadio Streaming

This project aims to create a production-ready, emc-compliant OpenHardware AudioStreaming-Product using OpenSource-Tools whenever possible.

georg-ottingergeorg ottinger 07/13/2014 at 10:270 Comments

Here are the schematics released under CC-BY-SA 3.0

The Power Section with LDOs, Linux Module and STM8 Microcontroller + UI (Leds)

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We use a Poly-Fuse (500mA) to protect the circuit from any mal-function. Also a diode is added to protect against reversed polarity. As we really want this device to last long we also added a Transzorb-Diode which protects for Over-Voltage Spikes. There are two LDOs (3v3 and 1v8) - we used LDOs to keep the design simple and not to go through the strougle of makeing Switching-Buck-Converters EMC-Compliant. You can also note that we are using a lot of ferrite beads in order to cut high frequency components aswell on signal and on power lines - maybe this design already exeterates the use of ferrite beads :) 

The XportPro Linux Module communicates via RX, TX RS-232 with the STM8 - The ResetLine for the STM8 and the Input-Button are also connected to the XportPro directly. We further added another controll Line from XportPro to STM8 which might be used in Future for more eleborated protocoll. You can find the details of the communication portocoll between XPortPro and STM8 here.

The STM8 drives the LEDs which are muxed and run at about 450 Hz. And in the upper left you can see some optional powermonitoring/reset circuits which are currently not populated.

The Audio Section with Audio DSP and Input- Output Amplifier

In the middle you can see the AudioDSP VS1063. On the left there are the Input Amplifieres. Once again you can note the ferrite beads that will cut off the (very) high frequency components - In order to reduce interference from for example cell phones that would introduce the well known ta-tat-tat-ta noise.

On the Output side we also added a Amplifier in order to add flexibility to the Output levels - May be the Output Amp is a bit too much as the VS1063 can drive moderate Loads on its own. But with this configuration it is possible to have Input and Output Signals approaching 5V Peak-to-Peak.

For the Amps we used high quality LME49721.

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You can download the EDA-Source of this project here. (License: CC-SA-BY 3.0)

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