FG085 miniDDS

The FG085 is a low cost yet versatile function generator capable of producing many different waveforms. As an easy-to-use tool operation of FG085 is very simple and straightforward. It is an ideal test/experiment tool for electronics hobbyists and students.

Model: FG085 miniDDS

Features

Features implemented as of current firmware

Generating continuous Sine, Square, Triangle, Ramp (up and down), and Staircase (up and down) signals
Generating servo test/control signals with user defined pulse width, amplitude, and cycle [ NEW ]
Setting of frequency (or period), amplitude, and offset is done with digits - quick and straightforward
Frequency (period), amplitude, and offset can be incrementally adjusted up and down with rotary encoder
Settings are memorized after power down.
Can be used as an adjustable DC voltage source by setting amplitude to 0

Features to be implemented (hardware support already in place)

Generating arbitrary signals
Generating special test signals NTSC/PAL video synchronous signal, and more
Generating sweeping signal with continuous phase
USB connection for waveform download and control
Programmable frequency, amplitude, and offset
Synchrous output
Burst output at trig

Application Ideas

producing continuous/swept waveforms* and servo test signals

Specification

Frequency range: 0 - 200KHz (Sine)
Frequency resolution: 1Hz
Period resolution: 1ms
Amplitude range: 0 - 10V peak-to-peak
Offset range: -5V - +5V
Memory depth: 256 bytes
Sample rate: 2.5Msps
Output impedance: 50 ohm
Power supply voltage: DC 15V
Current comsuption: < 150mA (without loading)
Dimension: 155 X 55 X 30 mm
Net weight: 100 gram

Resources

Frequency Range

In spite of that no limited range is set for frequency entry it should be aware of that there are practical ranges for output frequency due to the low resolution 8-bit DAC and slow sample rate (2.5Msps). Out of these ranges signal quality will degraded as larger distortions and jitters appear. The acceptable ranges depend on actual applications. For FG085 output frequency within following range is reasonably good for most applications.

Function	Range
Sine	0 – 200KHz
Square	0 – 10KHz
Triangle	0 – 10KHz
Ramp	0 – 10KHz
Staircase	0 – 10KHz

Servo Signal Settings

The following table lists the details about servo signal settings

Setting	Descriptions	Acceptable Range	Default
SV.PWmin	The minimum pulse width allowed	0 – 26000 uSec	1000
SV.PWmax	The maximum pulse width allowed	0 – 26000 uSec	2000
SV.PWmid	Pulse width corresponding to servo nurture position	0 – 26000 uSec	1500
SV.PWinc	[ADJ] step size in Servo Pos mode	0 – 26000 uSec	100
SV.RunStep	Step size of pulse width change in Servo Run mode	0 – 26000 uSec	100
SV.RunRate	Duration of one step in Servo Run mode	0 – 6.5 uSec	0.1
SV.Cycle	Servo signal cycle	0 – 26000 uSec	20000
SV.AMPmax	The maximum pulse amplitude allowed	0 – 10.0V	5.0V

Licensing

This documentation is licensed under the Creative Commons Attribution-ShareAlike License 3.0 Source code and libraries are licensed under GPL/LGPL, see source code files for details.

External Links

Links to external webpages which provide more application ideas, documents/datasheet or software libraries.