Be more flexible - enjoy better sound quality

• PCB supports recent RPi B as well as new RPi B+
• 1x PCM5102 - 24bit DAC [1], up to 384KHz, 32bit
• cost-effective alternative to HifiBerry [2], additional features
• DAC power decoupled from Raspberry Pi (improved audio quality due to very-low-noise LDO and hum filters in power rails)
• power Raspberry Pi from SPS and all your other extensions, capable to provide 2A current)
• wide range of DC wall adapters can be used, e.g. 9..15V DC, 1.5..2A or even an AC transformer (rectification on board, polarization protected)
• be flexible in terms of powering RPi, enjoy improved audio quality

Durio Sound

It is now Durio Sound

Please see: It's now Durio Sound

Overview

No need to solder any header or wire, just stack RPi-DAC-RCAplus on top of the RPi B+.

Stack vertically, RPi-DAC-RCA is on top of the RPi B+.

RPi-DAC-RCA could be stacked also below the RPi B+, it needs a bit of soldering effort (extend RPi B+ GPIO header pins, use a different 2x20 female header on RPi-DAC-RCAplus). This can give you a smaller height of the system.

Use the options in order to improve sound quality (e.g. very-low-noise LDO or SPS with 2A current capabilities).

The power input can be AC (from secondary AC transformer output) as well as DC with a wide voltage range of 9..15V.

You can use a DC wall adapter, e.g. 9..15V, 1.5..2A. There is a DC plug on PCB. It provides enough power to feed also extension boards.

Blockdiagram

The Standard version powers the DAC from RPi via 3.3V from RPi LDO, still using USB power supply on RPi B+

Option A: has a dedicated, very-low-noise LDO for the DAC (better sound quality)

Option B: provides a Switched Power Supply (SPS) which powers RPi and all your extentions (max. 2A)

The SPS option takes just direct AC transformer or any other DC input and can provide up to 2A current (e.g. for your extension boards), no USB power supply on RPi B+

You can upgrade the board any time or change to higher quality RPi-DAC without any system changes

Option AB: Power Supply for RPi and extension boards, LDO for decoupled DAC and SPS, no USB power supply

Option C: all - just instead of 3.5mm stereo plug two RCA connectors and LDO, SPS

Option D: use as Power Supply for RPi and extension boards, no DAC, no LDO, can be soldered anytime later

Schematics

The +3.3V is derived from the +5V from RPi (Option A) via low-noise LDO or from SPS (Option B) with an AC/DC wide-voltage-range input

The soft-mute feature (XSMT) can be used in order to watch the main power supply rail.

The DAC PCM5102 runs in PLL mode, no SCLK signal needed (which is not provided by the RPi).

The output signal is provided on a 3.5mm stereo jack or dedicated RCA connectors (Option C).

Remark: even with SPS soldered, it is possible to let it unpowered (no AC) and to power the RPi still via USB power supply. A diode allows to use the USB power supply still on RPi B+. BUT: never use both active at the same time.

Rasbian Linux Update

If you think anything necessary to change on your running system (Rasbian, Volumio) - NO!
Just change the HW module, use still the same driver (RPi-DAC or HifiBerry) and setup - and it works.

Important:The Rasbian Linux for the RPi B+ needs a modified kernel module (different I2S pin configuration). Please, get a patch for the older kernel or use really a Rasbian image which supports the B+ I2S. The Rasbian Linux for the older RPi B does NOT work.

You can change anytime from HifiBerry to RPi-DAC-RCAplus without changes on your system.
You can upgrade (solder additional parts) any time later on Standard RPi-DAC-RCAplus, e.g. add the SPS and any AC/DC input, having 1A current left for your extensions.

Rasbian /etc/modules

The latest Rasbian B+ installed on SD card you should put the following settings in your file /etc/modules:

			##snd-bcm2835
			snd_soc_core
			snd_soc_bcm2708_i2s
			bcm2708_dmaengine
			snd_soc_pcm1794a
			snd_soc_rpi_dac
				

So, you can run the RPi-DAC-RCAplus even with the RPi-DAC drivers and change anytime to the RPi-DAC later without any modifications.

If you have installed mplayer, e.g. via
  sudo apt-get install mplayer
you can play and test directly on command line, e.g. via:
  mplayer http://80.237.158.40/radio-brocken-128.mp3

PCB Large

Same size as Raspberry Pi, possible to mount on top (with GPIO connector with long pins) or below RPi (needs GPIO pin extensions soldered).

PCB can support older RPi B as well as newer RPi B+ (larger GPIO connector).

PCB Small

Smaller PCBi, RPi-DAC-RCA_Bplus_Short so that it fits on top of new Raspberry Pi B+.

Possible to use the GPIO for additional extension boards.

PCB can support older RPi B as well as newer RPi B+ (larger GPIO connector), just one standoff for older RPi B.

Final PCB Short for RPi B+

Smaller PCB so that it fits on top of new Raspberry Pi B+.

Possible to use the GPIO for additional extension boards, extend via GPIO pins, stack other boards.

PCB can support older RPi B as well as newer RPi B+ (larger GPIO connector), just one standoff for older RPi B.

Final PCB Short for recent RPi B

Smaller PCB so that it fits under the recent Raspberry Pi B.

Same PCB as used for RPi B+, one PCB for both RPi versions.

It uses the P5 I2S header, the GPIO for B+ is not used.

Design files and docs

RPi-DAC-RCAplus PCB (large), ExpressPCB format

RPi-DAC-RCAplus (short), ExpressPCB format

RPi-DAC-RCAplus (large) Solder Instructions and Parts

System Configuration

You can use almost all other RPi-DAC, T-DAC modules, even stacking with RPi-DAC is possible.

Exception: the RN52 Bluetooth module does not work directly on DAC PCM5102A, just on RPi-DAC with PCM1794A. You can use Bluetooth via RPi-DAC-SPDIF or RPi-DAC-FPGA module (with modified FPGA project).

So, you have the option to convert RPi-DAC-RCA into:

• an USB Sound Card with XMOS eval
• an USB Sound Card with RPi-DAC-IF and XMOS
• SPDIF/TOSLINK Sound Card with RPi-DAC-SPDIF or RPi-DAC-IF
• Bluetooth smartphone audio player via RPi-DAC-IF or RPi-DAC-FPGA with RN52
• Cost-effective USB Sound Card with STMF4Discovery

Almost all modules can accept AC and have on-board rectifiers. Some boards can be powered via DC direct connector without wiring (e.g. RPi).

Pictures

References

[1] see detailed circuit datasheets of original manufacturers

[2] http://www.hifiberry.com

[3] Overview (PDF)