Breakout for LinkIt Smart 7688 v2.0, succeeding the first version , now can better support the audio recording function. As it reserves the original pins of LinkIt Smart 7688, the board also integrates several frequently-used ports such as an Ethernet port, a 3.5mm audio port, and a Host port (USB Type-A Connector) for more peripherals, and along with 3 Grove ports to provide 2 UART and 1 I2C interfaces for the Grove-based electronics, it saves you a lot of work doing wirings in your smart IoT projects, makes your rapid prototyping even faster.
3.5mm headphone Jack(with Mic) which support OMTP and CTIA
Dimensions: 5.6mm x 8.2mm x 12mm
Input voltage: 5.0V(With USB Power port)
Operating voltage: 3.3V
Max Operating current: 2mA
Min Operating current: 800mA
Analog pin input voltage(on WM8960 ):2.7~3.6V(Analog pin input voltage on WM8960 for stereo can reach 5.5V at Max.)
Digital pin input voltage(on WM8960 ): 1.71~3.6V
some Build changes are needed to use Audio
We add i2s as audio i/o and define i2c to control the audio chip so a volume and other controls is present afterwards.
This is a `git patch` file so copy that to a file in the /openwrt bildroot folder and execute it with git patch <filename>.
and select sound/alsa-utils as well as the alsa-utils-tests, save and build.
After flashing the image you can use
with key “m”, “left-” and “right arrow” keys of your keyboard to navigate through the awesome software mixer of alsa where you have to set:
Be careful! High volumes can damage your ears.
Headphone (if you use external Amplifier or headphone via 3.5mm jack outlet) = choose volume
Speaker (About -10dB is a good test volume) = choose volume
Speaker AC = 0
Speaker DC = 0
Left Mixer Output PCM = unmute
Right Mixer Output PCM = unmute
Then try to play with alsa-utils-test like this in the terminal of the device:
speaker-test -t wav -c 2
You then should hear a woman speaking “Left”, “Right” ongoing until you abort with CTRL-c.
If you want to mix an external signal over the aux input try to higher the input 2 volumes in $alsamixer. (untested)
Try playing a .wav file with:
toh/seeed/linkit7688.txt · Last modified: 2020/11/21 12:40 by novski