Renesas RX231, Руководство пользователя

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Hear-it! Solution Kit 3 Description of Application Firmware
R12UZ0012EG0110 Rev. 1.10 Page 13 of 34
Apr 03, 2017
3.2 Audio Streaming Sample
The second sample, rx231_dsp_demo, demonstrates the application of a DSP FIR filter on the left or right
channel of an incoming audio signal from the line-in or microphone inputs. The modified audio stream is then
transmitted to the audio codec via DMA and the SSI peripheral and then out to the speaker and/or headphones.
Figure 3-2 shows a holistic outline of the audio streaming. As with the USB playback demonstration, the volume
control is implemented with a software attenuation function, with an option in the source code for control via the
codec directly. There further configuration available in the source code to select the left or right channel as the
input source, and the left, right or both channels as output source.
The output volume can be controlled by adjusting the potentiometer, R43. Switch SW3 cycles between the
different FIR filter profiles; Flat, High Pass, Low Pass, Band Pass where the audio is playing.
Figure 3-2 : Audio Streaming Mode
Caution:
Headphones should be connected to the 3.5mm line-out connector CN5. Connector CN6 is designed to
connect to a speaker only. It is not recommended to attach headphones to speaker connection CN6, as
damage to the headphones may occur. Refer to section 4.2.6 for further information.