Table of Contents
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.
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DDS signal generator schematic
DDS signal generator PCB
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.
https://www.youtube.com/results?search_query=USBASP+AVR+
The fuse configuration is:
Low: 0×CF
High: 0×59
Check:
OCDEN SPIEN BOOTSZ1 BOOTSZ2 SUT1 SUT0
BOM for mounting the function generator board
Last Update: 02/03/2023 16:01
| Part | Value | Description | Amount |
| Resistors | |||
| 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 | |
| Capacitors | |||
| 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 |
| Semiconductors | |||
| 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 |
| Miscellaneous | |||
| 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.
- Datasheet in PDF ATMEGA16A microcontroller IC
- PDF Datasheet LM358 operational amplifier IC
- PDF Datasheet 16 × 2 LCD displayHD44780
- PDF Datasheet iCL7660 voltage converter IC
- PDF Datasheet LM317 voltage regulator IC
- PDF Datasheet LD7550 voltage regulator IC
See also the version with PTH components
Detail of this project and source code on the Science Prog site
