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333 lines
11 KiB
Markdown
333 lines
11 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/AD985X/actions/workflows/jsoncheck.ym)l
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[](https://github.com/RobTillaart/AD985X/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/AD985X/blob/master/LICENSE)
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[](https://github.com/RobTillaart/AD985X/releases)
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# AD985X
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Arduino library for AD9850 and AD9851 function generators.
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## Description
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Library for the AD9850 and AD9851 function generators.
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These devices can produce a square and a sine wave
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| type | max frequency | phase (stepsize) |
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|:---------|---------------:|-------------------:|
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| AD9850 | 40 MHz | 0..31 x 11.25° |
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| AD9851 | 70 MHz | 0..31 x 11.25° |
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Note that at the max frequency the devices do not give a nice sine anymore.
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You need to check what is acceptable for your project.
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The library has a AD9850 as base class that implements the commonalities.
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The AD9851 is derived and has its own **setFrequency()** methods.
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Furthermore the AD9851 also has function to select the reference clock,
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a feature the AD9850 does not have.
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This feature improves the tuning for both low and high frequencies.
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**Warning**
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The library is not suitable for AD9852 as that is a function generator with
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way more functionality.
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Note: mainly tested on Arduino UNO. Tweaking for other platforms is expected.
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## Connection
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Schema break-out
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```
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TOP VIEW
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+-----------+
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| X-TAL |
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| L |
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VCC | o o | VCC
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CLK | o o | D0
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PUFD | o o | D1
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DATA | o o | D2
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RESET | o o | D3
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GND | o CCC o | D4
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QOUT1 | o CCC o | D5
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QOUT2 | o o | D6
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ZOUT1 | o o | D7 ----- SELECT SERIAL LOW
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ZOUT2 | o PP o | GND
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| PP |
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+-----------+
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XTAL = crystal
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L = LED
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C = chip
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P = potentiometer => for duty cycle square wave
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```
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### Multi device
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See **Multi_AD985X_devices.pdf**
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Discussion leading to the document see - https://github.com/RobTillaart/AD985X/issues/13
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The AD985X board can be connected with a SPI bus like interface.
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However there is **no Chip Select pin (CS)** so one must take other measures to control multiple AD985X devices.
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#### Trivial solution
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The trivial implementation is to give each device a set of unique pins.
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If you have pins to spare this is the perfect solution.
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#### Shared line solution
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A more common SPI solution is to share the data and clock lines.
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However that would typical set all AD985X devices simultaneously.
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So extra hardware is needed to prevent this.
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A possible solution is to put all needed lines behind an AND port that allows only
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communication when the **SELECT** is HIGH.
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```
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Arduino AND AD985X
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--------------------------------------------------
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+--------+
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SELECT ----| A |
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| Y |------- DATA
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DATA -----| B |
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+--------+
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+--------+
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SELECT ----| A |
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| Y |------- CLOCK
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CLOCK ----| B |
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+--------+
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+--------+
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SELECT ----| A |
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| Y |------- FQ_UD
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FQ_UD ----| B |
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+--------+
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+--------+
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SELECT ----| A |
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| Y |------- RESET
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RESET ----| B |
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+--------+
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```
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The **DATA** line of the device is connected to the output of an **AND** port.
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The inputs if the **AND** port are (a) the SPI bus **DATA** line and (b) the **SELECT** pin.
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Strictly for the **DATA** this is not needed as data will only clock in if there is a **CLOCK**.
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The **CLOCK** pin of the device is connected to the output of an **AND** port.
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The inputs if the **AND** port are (a) the SPI bus **CLOCK** line and (b) the **SELECT** pin.
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The **FQ_UD** pin of the device is connected to the output of an **AND** port.
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The inputs if the **AND** port are (a) the MCU **FQ_UD** line and (b) the **SELECT** pin.
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See FQ_UD note below.
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The **RESET** pin of the device is connected to the output of an **AND** port.
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The inputs if the **AND** port are (a) the MCU **RESET** line and (b) the **SELECT** pin.
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A typical IC to use is the **74HC08** which has 4 AND ports in it.
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In short this setup makes the lines 'switchable' pass through, with the **SELECT** line.
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It allows to have multiple AD985X devices, and even to share the SPI bus **DATA** and **CLOCK**
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lines with other SPI devices.
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### FQ_UD note
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It might be possible to connect a single FQ_UD line to multiple AD985X devices directly.
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The FQ_UD pulse would update the frequency and as this register is not changed, the FQ_UD
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pulse might just have no changing effect. To be investigated to confirm this.
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If confirmed this would change the above Shared line solution a bit.
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If the FQ_UD line can be shared directly it offers a way to start / change multiple
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devices at the same time.
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## Interface
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### Constructors
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- **AD9850()** 40 MHz signal generator
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- **AD9851()** 70 MHz signal generator, derived from AD9850 with some extra options.
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### Common interface
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- **void begin(uint8_t selectPin, uint8_t resetPin, uint8_t FQUDPin, uint8_t dataOut = 0, uint8_t clock = 0)**
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For hardware SPI only use the first three parameters,
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for SW SPI you need to define the data and clock pin too.
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- selectPin = chip select. The library uses HIGH as active and LOW as not selected.
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- resetPin = reset
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- FQUD = Frequency UpDate Pin
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- **void reset()** resets the function generator.
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- **void powerDown()** idem.
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- **void powerUp()** idem.
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- **bool setFrequency(uint32_t freq)** SetFrequency sets the frequency and is limited by the
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MaxFrequency of the class used.
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Returns false if limited.
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For the AD9850 => 40 MHz, for the AD9851 => 70 MHz.
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- Note that the quality of the signal gets less at higher frequencies.
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- Note setFrequency is affected by the autoUpdateFlag.
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- **bool setFrequencyF(float freq)** SetFrequencyF sets the frequency with a float with a maximum of **two** decimals.
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- Note that a float only has a mantissa of 6-7 digits so for frequencies above above ~1.000.000 = 1MHz all decimals are lost.
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- Note setFrequencyF is affected by the autoUpdateFlag.
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The frequency is limited by the MaxFrequency of the class used.
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Returns false if limited.
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- **uint32_t getMaxFrequency()** returns the maximum frequency that can be set. For the AD9850 this is 20 MHz.
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For the AD9851 this is 70 MHz.
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- **float getFrequency()** returns the frequency set. As it returns a float it might loose some accuracy at higher frequencies.
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- **bool setPhase(uint8_t phase = 0)** set the phase in units of 11.25° 0..31 allowed.
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Default it sets the phase to 0.
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Returns false if phase > 31, no change to phase in that case.
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- **uint8_t getPhase()** returns the phase set, 0 by default. One need to multiply by 11.25° to get the actual angle.
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### Calibration
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**Warning:** use with care.
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- **void setCalibrationOffset(int32_t offset = 0)** sets an offset to calibrate the frequency.
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- **uint32_t getCalibrationOffset()** reads back the offset set.
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- **uint32_t getFactor()** internal factor, for debugging
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Note: **reset()** resets the offset to 0..
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Note: setting the offset reduces the range of frequencies (at the ends of scale).
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### Auto update / manual update
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(new since 0.2.2)
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**Warning:** use with care.
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- **void setAutoUpdate(bool update)** sets the autoUpdate flag, default set to true.
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- **bool getAutoUpdate()** reads the autoUpdate flag.
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- **void update()** manually toggle the FQ_UD flag to update the frequency.
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Manual updating allows one to prepare the frequency, and actually apply
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it at a later moment.
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Note: The default of the autoUpdate flag is true.
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Note: **reset()** resets the autoUpdateFlag to true.
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### Hardware SPI
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To be used only if one needs a specific speed.
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- **void setSPIspeed(uint32_t speed)** set SPI transfer rate.
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- **uint32_t getSPIspeed()** returns SPI transfer rate.
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- **bool usesHWSPI()** returns true if HW SPI is used.
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### ESP32 specific
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This functionality is new in 0.3.1.
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- **void selectHSPI()** in case hardware SPI, the ESP32 has two options HSPI and VSPI.
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- **void selectVSPI()** see above.
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- **bool usesHSPI()** returns true if HSPI is used.
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- **bool usesVSPI()** returns true if VSPI is used.
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The **selectVSPI()** or the **selectHSPI()** needs to be called
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BEFORE the **begin()** function.
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#### ESP32 experimental
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- **void setGPIOpins(clk, miso, mosi, select)** overrule GPIO pins of ESP32 for hardware SPI.
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Needs to be called AFTER the **begin()** function.
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```cpp
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void setup()
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{
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freqGen.selectVSPI();
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freqGen.begin(15);
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freqGen.setGPIOpins(CLK, MISO, MOSI, SELECT); // SELECT should match the param of begin()
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...
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}
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```
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### AD9850 specific
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The AD9850 has no specific functions.
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### AD9851 specific
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- **void setRefClockHigh()** set reference clock to 180 Mhz.
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- **void setRefClockLow()** set reference clock to 30 Mhz.
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- **uint8_t getRefClock()** returns 30 or 180.
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- **void setAutoRefClock(bool arc)** sets a flag so the library switches automatically
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to the reference clock of 180 MHz when the frequency is set above 10 MHz and
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to 30 MHz when the frequency is set to 10 MHz or lower.
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The initial value is **false** == OFF for backwards compatibility.
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- **bool getAutoRefClock()** returns true if autoRefClock is set.
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- **void setARCCutOffFreq(uint32_t Hz = 10000000UL )** set cut off frequency
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for the auto reference clock.
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Maximum value is 30 MHz, typical is 10 MHz.
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- **uint32_t getARCCutOffFreq()** returns cut off frequency set.
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- Note: the autoRefClock mode does **NOT** automatically adjust the calibration offset.
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- Note: **reset()** does **NOT** reset the autoRefClock flag.
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## Operation
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See examples.
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### Operational notes
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- The quality of the signal becomes less at higher frequencies.
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Switch the reference clock to find your optimal quality.
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- If the calibration offset is not 0, it needs to be set by the user after every startup,
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and after switching the reference clock.
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The user is also responsible to store it e.g. in EEPROM to make it persistent.
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- Experimental parts may change or removed in the future.
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## Future
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#### Must
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#### Should
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- examples for ESP32 HWSPI interface
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- do tests on ESP32
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- performance measurements
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- unit tests for
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- bool setFrequency
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- bool setPhase
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#### Could
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- move code to .cpp
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- create defines for MAGIC numbers (defaults)
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- should other void function return bool?
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- setARCCutOffFreq() ?
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#### Wont
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