February 2013
Linux iMX23 audio loop (or using the iMX23 as an amplifier)
As usual when working with embedded systems every component saved seems like gold to the HW guys (no matter how much software hassles or future limitations this may cause!) and in this context lately I’ve been working on the idea to use the Freescale iMX23 processor, that was anyway present in the project for other needs, as an audio amplifier to pilot a small speaker with no special volume requirements. Basically the output of a GSM module (audio out) was connected to the MIC input of the iMX23 and then the output to the speaker, just with little strictly needed passive electronics in between. As by the datasheet the processor should be able to pull out till 1.9W at 4Ω and there were some interesting registers to play with, even if not documented so very clearly nor seemed to be used anyhow in the audio driver provided. The software base used was the LTIB based BSP provided by Freescale, including their kernel patches for a 2.6.31 kernel.
Audio BM_AUDIOOUT_TEST_ADCTODAC_LOOP Drivers Embedded Freescale Imx23 Linux Linux Drivers Linux Embedded Loopback Teaching Material
4 minutes