![]() ![]() ![]() In this case K8, C15 and C16 can be left unmounted. +4.74 and -4.81 V are supplied by the DAC and +3.3 V by the Raspberry Pi (expansion connector pin 1). ![]() ![]() When used as an add-on no additional power supply is needed. To control the PGA2311 we use a microcontroller from Atmel (ATtiny series). Called ‘Digitally-Controlled Analog Volume Control’ it’s controlled by a Serial Control Interface, also has selectable zero crossing detection and a mute function. We used it because of its excellent low noise and low distortion specifications and it works on a symmetrical 5 V power supply. The volume controller chosen is an integrated circuit from Texas Instruments, the PGA2311. So the only option is additional hardware. Discarding bits in software is not an option. As the name points out it’s a volume control for our RPi DAC, because the IC we used (PCM1794A) doesn’t have one. Volume and/or an application running on the Raspberry Pi can be controlled by six buttons (a seventh button is used for storing a preferred setting of the volume level) and IR remote control. This PCB is in first place an add-on for our Raspberry Pi Audio DAC (160198-1) but it’s also usable for general use (separate symmetrical 5V supply needed then). Downloading of this magazine article is reserved for registered users only. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |