YannLocatelli
commented
2 years ago Comments
DACDriver and DACTimer #302
AnalogOut of mbed cannot use the DMA, a tool that can transfer data from a port to another (here from SRAM to DAC output) and allow to free CPU from this task. DACDriver and DACTimer implement an "AnalogOut" using the DMA with ST DAC driver only.
DAC output is used to vary tension at a specific rate to generate waves of vibrations & sounds into haptic vibrator. To synchronise the output at a specific rate, a Timer is used and due to the nature of DAC (implement ST driver and not mbed), the Timer is also from ST and its configuration vary from mbed Timer. There are only 2 available for DAC & DMA and their max frequency can go from [1.6KHz to 108MHz (max of the MCU)]. DACTimer wrap the ST Timer to fit with ST DAC to allow it to output data at a specific rate.
DACDriver is a wrapper of ST DAC. It uses DACTimer and also a DMA. Apart from hid configuration, DMA can notify callback when the last data of first and second half of its internal buffer are transferred . This principle is used in spike to call callbackTest and also later on to load next data of sound or vibration.
DACTimer and DACDriver are fully implemented, not unit tested and have to be renamed to fit with Leka’s style. The spike associated is lk_dac.
Complementary documents: [Reference Manual]
CoreAudio
WAVFile is a FIL wrapper and considers a file as WAV format and gather information in the header of the file (RIFF).
WAVReader convert data stored in a file (WAVFile) into correct format → Data is stored in uint8_t, data sound is encoded in int16_t in mono. WAVReader do the transfer from SD to SRAM.
CoreAudio uses WAVReader to get sound data and DACDriver to play sound data. It also controls the volume. It also refill the DMA buffer of DACDriver when it reaches the first or second half.
There is a high-pass filter at 100 Hz to avoid the resonance at 60 Hz. Most of suggestion can be found in related issue #303. One remaining task is to set DACTimer and DACDriver internal to CoreAudio.
CoreAudio is fully implemented but not unit tested. The spike associated is lk_audio.
CoreVibration #306
An envelope is applied on a constant frequency to modulate amplification and render a specific vibration.
The resonance [Link] is not handled.
CoreVibration is considered as an advanced draft.
ladislas
Description
Work done by Samuel & Maxime during their internship from June '21 to August '21.
They worked on Audio playback, DAC and vibrations.
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