Wolfson audio codec adds touchscreen interface support

The WM9712L audio codec from Wolfson Microelectronics Ltd features a streaming data touchscreen interface into a 7-by-7mm chip-scale QFN package, suitable for integration into PDAs, cellphones, and other handheld consumer devices.

The device operates from supply voltages between 1.8V and 3.6V with a core voltage down to 1.42V - almost half that of previous devices. Other features include an on-chip speaker driver, graphic equalizer, GPIO pins, and 5-wire touchscreen support.

The WM9712L is compatible with the AC'97 standard, carrying audio, touchscreen and control data on a single serial interface. Variable-rate support is built-in to support audio sample rates used in WinCE systems. This removes the need for PLL circuits or sample rate conversion algorithms that slow down the CPU.

The continuous-mode touchscreen interface has been designed to reduce CPU loading, as data can be written directly to a DMA buffer at a pre-programmed rate. This eliminates time-consuming polling routines to access touchscreen data.

The WM9712L is also claimed to be first audio codec to provide all the audio functions for a smartphone, mixing voice with other audio signals like MP3 music, and connecting directly to stereo headphones, a phone receiver, and a separate 8-ohm loudspeaker.