Simple arduino sketch for driving DDS AD9850
This little sketch is useful for driving the cheap Analog Device DDS AD9850.
This chip, equipped with a 125 MHz crystal oscillator, is capable to produce a sine wave up to 40 MHz.
All the experiments are made using an HC-SR08 PCB, which came with the DDS, the crystal and pin risers already mounted.
Connect the following pins between Arduino and the PCB:
| Arduino | HC-SR08 PCB with AD9850 |
|---|---|
| 8 | RESET |
| 9 | DATA |
| 10 | FU_UD |
| 11 | W_CLK |
For serial programming, AD9850 requires pin D2 to be connected to ground, and pins D1 and D0 to VCC.
Open a serial terminal in Arduino serial port, at 115200 baud, configured as 8N1.
There are 2 commands:
- F: change frequency
- R: DDS reset
To set 10.0 MHz, input F10000000 and press RETURN, you will read:
Frequency (Hz): 10000000 - Number: 343597383 - Sending to DDS: 11100010100001110101111000101000 - Completed!
To set 28.215 MHz, input F28215000 and press RETURN, you will read:
Frequency (Hz): 28215000 - Number: 969460018 - Sending to DDS: 01001100100100110001001110011100 - Completed!
- First value is the frequency request.
- The second value is the unsigned 32-bit integer which will be sent to the DDS.
- The third value is the same 32-bit integer in binary form, written in big endian format.
To reset DDS, input R and press RETURN, you will read:
DDS reset... - Completed!
The value of the 32-bit word is computed with this formula:
in which:
- W is the output word (unsigned 32-bit integer)
- f is the frequency requested
- C is the DDS clock
Arduino sketch for DDS AD9850 Copyright (C) 2019 Luca Cireddu (sardylan@gmail.com)
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.