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diff --git a/docs/source/arduino/analogread.rst b/docs/source/arduino/analogread.rst deleted file mode 100644 index d0fa5a1..0000000 --- a/docs/source/arduino/analogread.rst +++ /dev/null @@ -1,134 +0,0 @@ -.. highlight:: cpp - -.. _arduino-analogread: - -analogRead() -============ - - -Signature ---------- - -``int analogRead(int pin);`` - - -Description ------------ - -Reads the value from the specified analog pin. The Maple board -contains a 16-channel, 12-bit analog to digital converter. This means -that it will map input voltages between 0 and 3.3 volts into integer -values between 0 and 4095. This yields a resolution between readings -of 3.3V / 4096 units, or 0.8 millivolts. However, a number of factors -interfere with getting full accuracy and precision. For more -information, see :ref:`adc`. - -Before calling analogRead() on a pin, that pin must first be -configured for analog input, using :ref:`arduino-pinMode`. - -The input range and resolution can be changed using -:ref:`arduino-analogReference`. - -It takes about 0.8 microseconds (.0000008 seconds) to read an analog -input, so the maximum sample rate using this function is approximately -1.3 million samples per second [#fsamp]_. - - -Parameters ----------- - -**pin** - - The number of the analog input pin to read from. Header pins on the - Maple with ADC functionality (marked as "AIN" on the silkscreen) - are: - - 0, 1, 2, 3, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 27, 28 - - Note that pins 3, 27, and 28 are not marked AIN on the silkscreen - for Maple revisions through Rev 5, however, they **do work** as - analog input pins. - -Returns -------- - -Converted input voltage as an ``int``, with value 0 to 4095, inclusive. - - -Note ----- - -If the analog input pin is not connected to anything, the value -returned by analogRead() will fluctuate based on a number of factors -(e.g. the values of the other analog inputs, how close your hand is to -the board, etc.). - - -Example -------- - - :: - - - int analogPin = 3; // potentiometer wiper (middle terminal) connected to analog pin 3 - // outside leads to ground and +3.3V - int val = 0; // variable to store the value read - - void setup() { - pinMode(analogPin, INPUT_ANALOG); - SerialUSB.begin(); - } - - void loop() { - val = analogRead(analogPin); // read the input pin - SerialUSB.println(val); // debug value - } - - -Arduino Compatibility Note --------------------------- - -The Arduino board contains a 6 channel (8 channels on the Mini and -Nano, 16 on the Mega), 10-bit analog to digital converter. This means -that it will map input voltages between 0 and 5 volts into integer -values between 0 and 1023. This yields a resolution between readings -of: 5 volts / 1024 units or, .0049 volts (4.9 mV) per unit. On the -Arduino, the input range and resolution can be changed using their -implementation of `analogReference() -<http://arduino.cc/en/Reference/AnalogReference>`_\ . - -On the Arduino, it takes about 100 microseconds (0.0001 s) to read an -analog input, so the maximum reading rate is about 10,000 times a -second. - - -See also --------- - -- :ref:`ADC note <adc>` -- :ref:`analogReference <arduino-analogreference>` -- `(Arduino) Tutorial: Analog Input Pins <http://arduino.cc/en/Tutorial/AnalogInputPins>`_ - - -.. rubric:: Footnotes - -.. [#fsamp] This is based on the current configuration of a 55.5 cycle - sample time, at 72 MHz. However, the minimum sample time *possible* - is 1.5 cycles, leading to a theoretical maximum of approximately 48 - million samples per second (of course, doing anything with the - readings also consumes cycles, so this maximum can't be reached in - practice). - - See the `STM32 Reference Manual <full-manual>`_, ยงยง11.12.4--5 - (pp. 225--226), for more information on the low-level bit twiddling - currently necessary to change the sample time. For examples of how - the ADCs are configured in libmaple, see `adc.h - <http://github.com/leaflabs/libmaple/blob/master/libmaple/adc.h>`_ - and `adc.c - <http://github.com/leaflabs/libmaple/blob/master/libmaple/adc.c>`_\ - . Be aware that changing the sample time has important - consequences related to the impedance of the device connected to - the input pin. If you want to make changes, as a minimum, you - should first read ST's application notes on `ADC modes - <stm32-adc-modes>`_ and `ADC oversampling - <stm32-adc-oversampling>`_. |