DDS signal generator with AVR sine, square, ECG 8Mhz

DDS signal generator with AVR sine, square, ECG 8Mhz

DDS signal generator with AVR circuit with Atmega16 microcontroller with BNC output. One square wave output up to 8MHz and another DDS output with sine wave, square, triangle, ECG, Noise, Inverted Sawtooth. The offset can be adjusted from +V to -5V, the amplitude can be adjusted from 0 to 10V by potentiometer. With keys to access the functions.I have already posted a PTH component version and this time we used SMD components, plus bigger keys, BNC connector output, 16 × 2 LCD and adjustment potentiometers.

The DDS output is used for all complex signals generated through the R2R resistor network and is adjusted by LM358 offset and amplitude regulation circuits. Two potentiometers control the offset and amplitude.

The power supply I used LM317 voltage regulator set to 9V output and a symmetrical power supply generator by ICL7660 to power the operational amplifier. To power the Atmega16 microcontroller, I used LDO LD7550 voltage regulator. If you prefer, you can configure the Lm317 to run at 12V.

The crystal is type SMD-3225-4P, the Lm358 IC must be original, the symmetrical voltage generator can be original Renesas or similar, the voltage regulators can be of any brand.

Buy equivalent circuit in AliExpress

Buy equivalent circuit in Banggood

DDS signal generator schematic

Schematic Circuit Dds Signal Generator With Avr

DDS signal generator PCB

Pcb Printed Circuit Board Top Dds Signal Generator
Pcb Bottom Printed Circuit Board Dds Signal Generator
View Of Components Top Dds Signal Generator
Top Component View Dds Signal Generator Bottom Part

Features DDS signal generator sine function, square, ECG 8Mhz

  • High-speed (HS) output signal up to 65.534Hz (Sine, Square, Triangular, Sawtooth, and others) or 8 MHz at high-speed (Square Wave) output
  • DDS with variable amplitude and offset.
  • DDS signals: sine, square, Sawtooth, Triangle, ECG, and noise.
  • 2×16 LCD – Intuitive menu with 6 keys.
  • Frequency setting steps: 1, 10, 1000 and 10000 KHz
  • Restores the last setting after power-up.
  • Has two outputs – One for DDS signal and one for high speed.
  • Power supply with LM317 IC, and can use higher voltage source up to 35V.
  • Symmetrical source for the operational amplifier using ICL7660, to generate +9 and -9V.
  • Power supply: 12 to 35V DC
  • DDS signal frequency: 1 to 65.534Hz
  • Waveforms: Sinusoidal, Square, Triangular, Sawtooth, Inverted Sawtooth, ECG, Noise
  • HS Signal Frequency: 1, 2, 4, 8 MHz
  • Microcontroller used: Atmega16A
  • Setting: Offset and amplitude
  • Display: 16 × 2 LCD with backlight
  • Consumption: About 55mA with backlight

To program the microcontroller, you can use some TQFP44 to AVR adapter or, via ICSP, you can use professional recorders like Minipro or even the low cost Atmel USBasp ISP.

The fuse configuration is:
Low: 0×CF
High: 0×59


BOM for mounting the function generator board

Last Update: 02/03/2023 16:01

Part Value Description Amount
R3, R12, R13, R14, R15, R16, R17, R18 10k 103 or 1002 — SMD 0603 1% 8
R1 1.5k 152 — SMD 0603 1
R2 240 2540 — SMD 0603 1
R4, R5, R6, R7, R8, R9, R10, R11, R19 20k 203 or 2002 — SMD 0603 1% 9
R20, R23 100k 104 — SMD 0603 2
R21 100 101 — SMD 0603 1
R22 4.7 4R7 — SMD 0805 1
R24 12k 123 — SMD 0603 1
P1 1k 102 — Potentiometer 1K — Offset 1
P2 50k 503 — Potentiometer 50K — Amplitude 1
P3 10K Trimpot SMD de 3 mm — BOURNS TC33X-2-103E or equivalent
C1, C2, C5, C6, C10, C11, C12, C15 10uF/16V Tantalum Capacitor 3216 (CASE-A-3216) 8
C4 10uF/50V 1206 SMD Ceramic Capacitor 1
C3, C7, C8, C9, C13, C14, C16, C17, C18, C19 100n SMD 0603 ceramic capacitor – C3 50V or more 10
IC1 LM317 Adjustable Positive Voltage Regulator – TO-252-2 (DPAK) 1
IC2 ICL7660 Renesas Symmetrical Voltage Generator – SOIC-8 1
IC3 HT7550 Positive voltage regulator 5V ±2% tolerance – SOT89 1
IC4 Atmega16a Atmega Microcontroller (Microchip) TQFP44 1
IC5 LM358 Operational Amplifier – SOIC-8 1
LCD1 LCD-HD447804 Display LCD 16 × 2 with backlight 1
Q1 16MHz Crystal — SMD-3225-4P 1
S1 RESET Tactile key – B3F-40XX or equivalent 12×12×7.3 mm – Reset the board (optional) 1
S2 UP Touch key – B3F-40XX or equivalent 12×12×7.3 mm – UP menu 1
S3 RIGHT Tactile Key – B3F-40XX or equivalent 12×12×7.3 mm – Right menu 1
S4 START/STOP Tactile key – B3F-40XX or equivalent 12×12×7.3 mm – Start/Stop 1
S5 LEFT Tactile Key – B3F-40XX or equivalent 112×12×7.3 mm – Left 1
S6 DOWN Tactile key – B3F-40XX or equivalent 12×12×7.3 mm – Below 1
J1 12V DC JACK 1
J2 DDS BNC connector – DDS output 1
J3 HS BNC connector – HS output 1
JP1 AVR-ISP-6 ICSP connector – For programming the Atmega16 – Can be 2 rows of pin header. 1
Solder, Wires, PCB, Box, Power Supply.
Download the files for this PCB assembly in Gerber, PNG, Postscript, and PDF – All for free.



See also the version with PTH components

Detail of this project and source code on the Science Prog site



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About the author blog author. Electronics technician for the technical school of Brasilia - Brazil. Interested in electronics, circuits and technology in general.

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