Arduino SPI library for AD9850

F4GOJ Christophe [email protected]

August 2014

Upgrade to SPI F4GOH Anthony [email protected]

This library uses the Serial Peripheral Interface (SPI) to accelerate the update of the AD9850 from 700µs in software serial to 90µs (54µs for the deltaphase calculation and 36µs for the transfert)

AD9850 datasheet at http://www.analog.com/static/imported-files/data_sheets/AD9850.pdf

Use this library freely.

Installation

To use the AD9850SPI library:

• Go to https://github.com/F4GOJ/AD9850SPI, click the Download ZIP button and save the ZIP file to a convenient location on your PC.
• Uncompress the downloaded file. This will result in a folder containing all the files for the library, that has a name that includes the branch name, usually AD9850SPI-master.
• Rename the folder to AD9850SPI.
• Copy the renamed folder to the Arduino sketchbook\libraries folder.

Usage notes

The AD9850SPI library instantiates a DDS object, the user does not need to do this.

To use the AD9850SPI library, the SPI library must also be included.

#include <AD9850SPI.h> //http://github.com/F4GOJ/AD9850SPI
#include <SPI.h>       //http://arduino.cc/en/Reference/SPI (included with Arduino IDE)

Hardware connections :

• W_CLK -> D13 arduino UNO/NANO, D52 MEGA
• FQ_UD -> any pin except 10 and 12 UNO/NANO, 50 and 53 MEGA
• DATA/D7 -> D11 arduino UNO/NANO, D51 MEGA
• RESET -> any pin except 10 and 12 UNO/NANO, 50 and 53 MEGA

Functions :

begin(int w_clk_pin, int fq_ud_pin, int reset_pin)

Description

Initialize the output pins and master reset the AD9850

Syntax

DDS.begin(w_clk, fq_ud, reset);

Parameters

w_clk : SPI SCK output pin (13 on a UNO/NANO, 52 on a MEGA) (int)
fq_ud : Frequency update pin, any pin except 10 and 12 UNO/NANO, 50 and 53 MEGA. (int)
reset : Reset output pin, any pin except 10 and 12 UNO/NANO, 50 and 53 MEGA. (int)

Returns

None.

Example

void setup(){
 DDS.begin(13, 8, 9);
}

calibrate(double trim_frequency)

Description

Compensation of crystal oscillator frequency.
Can be used at any time after initialization.

Syntax

DDS.calibrate(trim_freq);

Parameters

trim_freq : Adjust around 125000000 to match the real crystal oscillator frequency. (double)

Returns

None.

Example

void setup(){
 DDS.begin(13, 8, 9);
}

void loop(){
 DDS.calibrate(124999000);
}

setfreq(double frequency, int phase)

Description

Sets the output frequency of the AD9850 and the phase of the signal.

Syntax

DDS.setfreq(frequency, phase);

Parameters

frequency : Output frequency in Hz. (double)
phase : Sets the phase of the output signal, coded on 5 bits allows 32 phase steps of 11,25° each. (int)

Returns

None.

Example

double frequency = 10000000;
int phase = 0;
DDS.setfreq(frequency, phase);

down()

Description

Power down mode reducing the dissipated power from 380mW to 30mW at 5V

Syntax

DDS.down();

Parameters

None.

Returns

None.

Example

DDS.down();

up()

Description

Wakes-up the AD9850 from power down mode.

Syntax

DDS.up();

Parameters

None.

Returns

None.

Example

DDS.down(); // Entering power down mode

// some code doing something

...

DDS.up(); // WAKE-UP !!! :)