User`s guide

Intel
®
StrongARM
®
SA-1110 Microprocessor Development Board User’s Guide 4-29
Hardware Considerations
• Software control of audio destinations
• Any OS managed digital audio streams or analog audio source to mini-speaker or UBC
microphone input or radio microphone input or headset or headphones
• Automatic gain control for microphone1 inputs
• Treble, bass and volume control
4.12.1 Stereo Codec
A Philips UDA1341 I2S 16 bit delta sigma stereo codec is provided on the SA-1110 Development
Board through the glue logic to the SA-1110 SSP port. The UDA1341 on the SA-1110
Development Board provides high quality stereo sound input and output for entertainment sound
and speech recognition application support without requiring the SA-1111 companion chip. The
SA-1110 Development Board provides a UDA1341 digital loopback that allows the UDA1341 to
be used as a systems audio routing and mixing resource without having to set up the SA-1110 SPI
port to access the UDA1341.
A 0.250 mW per channel audio amplifier drives the internal speaker or the 3.5 mm standard stereo
jack for high quality stereo output to a headset.
Volume, treble and bass settings are by program control of the UDA1341. Volume control up/down
switches may be allocated from the general purpose system switches as required by the application.
The UDA1341 is interfaced to the SA-1110 SSP port using a small amount of CPLD glue logic as
shown in Figure 5-3.
The UDA1341 also requires a three wire control interface known as L3. This control interface is
similar to I
2
C* in that it may be implemented using programmed I/O and GPIO pins. The L3 bus
and SMbus bus share the same GPIO pin.
4.12.2 L3 Bus
The UDA1341 L3 bus utilizes a simple serial protocol similar to the I
2
C—see the UDA1341
specifications for details. The L3 includes a clock pin, a data pin, and a mode pin. These three slow
speed signals are connected to the SA-1110 GPIO pins and are driven with software to implement
the L3 protocol.