docs: Add missing peripheral driver docs (ADC, DAC, RTC I/O, I2S)

2017-02-16 13:59:50 +11:00
parent 21964a42fb
commit bfdfcbfaef
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+Digital To Analog Converter
+===========================
+
+Overview
+--------
+
+ESP32 has two 8-bit DAC (digital to analog converter) channels, connected to GPIO25 (Channel 1) and GPIO26 (Channel 2).
+
+The DAC driver allows these channels to be set to arbitrary voltages.
+
+The DAC channels can also be driven with DMA-style written sample data, via the :doc:`I2S driver <i2s>` when using the "built-in DAC mode".
+
+For other analog output options, see the :doc:`Sigma-delta Modulation module <sigmadelta>` and the :doc:`LED Control module <ledc>`. Both these modules produce high frequency PWM output, which can be hardware low-pass filtered in order to generate a lower frequency analog output.
+
+
+Application Example
+-------------------
+
+Setting DAC channel 1 (GPIO 25) voltage to approx 0.78 of VDD_A voltage (VDD * 200 / 255). For VDD_A 3.3V, this is 2.59V::
+
+  #include <driver/dac.h>
+
+  ...
+
+      dac_out_voltage(DAC_CHANNEL_1, 200);
+
+API Reference
+-------------
+
+Header Files
+^^^^^^^^^^^^
+
+  * `components/driver/include/driver/dac.h`
+
+Enumerations
+^^^^^^^^^^^^
+
+  .. doxygenenum:: dac_channel_t
+
+Functions
+^^^^^^^^^
+
+  .. doxygenfunction:: dac_out_voltage
+
+