This version (27 May 2022 11:01) was approved by erbe reyta.The Previously approved version (27 May 2022 10:11) is available.
Table of Contents
EVAL-CN0511-RPIZ Overview
Instruments that operate at radio frequency (RF) range with features like low distortion, ultra low phase noise, and portable signal generator are difficult to provide at reasonable cost.
The system shown below in Figure 1 is an entirely self-contained DC to 6GHz signal generator. It only requires the Raspberry Pi (RPi) to operate. The RF Digital-to-Analog Converter (DAC), controlled using a 100MHz Serial Peripheral Interface (SPI) from the RPi, allows for single tone, phase coherent, and fast frequency hopping across the spectrum. All the clocking is generated using an onboard crystal so no external clock source is required. All necessary power rails are converted from the RPi into various supply voltage requirements of the RF signal generator.
The system is designed to simplify the input requirements, help optimize the signal paths, and reduce external cables and components. This circuit can act as a standalone laboratory equipment, or can be incorporated as a module into automatic test equipment. Its small size makes it particularly attractive when multiple channels are required. This RPi compatible solution makes high-speed signal generation more accessible and economical.
Figure 1. EVAL-CN0511-RPIZ Evaluation Board
Features
- Supports RF signal synthesis and pulse modulation of up to 9GHz
- High dynamic range and signal reconstruction bandwidth
- Fully supports zero intermediate frequency (IF) and other dc-coupled applications
- Exceptional spectral flatness and output return loss
- Onboard free-running 122.88MHz precision oven-controlled crystal oscillator (OCXO)
- Supports both local touchscreen (TFT LCD screens) and HDMI display
- Features low output ripple with low output capacitance
- Available SPI, USB, and Ethernet communication interfaces
- No bulky heat sinks required
Documents Needed
- CN0511 Circuit Note
Equipment Required
- Hardware
- EVAL-CN0511-RPIZ Circuit Evaluation Board
- Raspberry Pi 3B+
- 5V, 2.5A power supply with micro USB connector
- SMA to SMA cable
- 16GB or larger SD card
- USB keyboard and mouse
- HDMI to HDMI cable
- Monitor with HDMI port
- Software
- ADI Kuiper Linux image
Block Assignments
Figure 2. EVAL-CN0511-RPIZ Block Terminal Assignments
- Connector P1 is the terminal block for optional external +5V input supply.
- Connector P2 is the 40-pin connector for Raspberry Pi.
- Connector P3 is the terminal block for optional external +3.3V input supply.
- Connector J1 is the RF output from the EVAL-CN0511 board.
- Connector J2 is the External Clock Reference RF input for the EVAL-CN0511 board.
Running the System
Figure 3. Test Setup Functional Block Diagram
Figure 4. Hardware Connections of CN0511
To set up the circuit for evaluation, consider the following steps:
- The EVAL-CN0511-RPIZ connects to Raspberry Pi board through the 40-pin connector.
- Burn the SD card with the proper ADI Kuiper Linux image. Insert the burned SD card on the designated slot on the RPi.
- Connect the system to a monitor using an HDMI cable through the mini HDMI connector on the RPi.
- Connect a USB keyboard and mouse to the RPi through the USB ports.
- Connect the RF load/signal analyzer to the dedicated output connectors from the EVAL-CN0511-RPIZ.
- Power on the RPi board by plugging in a 5V power supply with micro-USB connector.
- Open the terminal and configure the device tree overlay file. See software section for detailed instructions. Make sure to reboot the RPi after saving the config.txt file.
- An optional external +5V power supply can be used to power the EVAL-CN0511-RPIZ and the RPi Board
- An external clock source can be used for system clock reference.
Solder Jumper Settings and Configuration
The CN0511 reference design is supplied with an ultra-low phase noise CMOS voltage-controlled crystal clock oscillator. If the performance needs can’t be met, an external option is available, which is limited of up to 500MHz clock source input. And this external clock source can be connected through the on-board SMA port.
The CN0511 has a solder jumper (JP1) which configures different settings as shown below for the clock source. The default position of JP1 is set at A-COM.
Figure 5. EVAL-CN0511-RPIZ Clock Source Schematic Diagram
Figure 6. EVAL-CN-0511-RPIZ Clock Source Assignment
Hardware Setup
Setting up and Connecting the Raspberry Pi
RPi connects to the EVAL-CN0511-RPIZ through 40-pin connector P2.
Figure 7. Input Power Supply Connection Options of CN0511
Input/ Output Connections
RF Output
A spectrum analyzer can be can be used to observe the generated RF output from J1 on the EVAL-CN0511-RPIZ.
External Clock Reference Option
An external clock reference can be used to generate external clock reference to improve system noise.
Figure 8. Input and Output Connection Guide of CN0511 Raspberry Pi with a Spectrum Analyzer and External Clock Source
To use an external single-ended reference input (REFIN) up to 500MHz, connect a single-ended low noise source to REFIN. Set solder link JP1 to B – COM to switch the clock reference from the on-board OCXO to an external clock source.
Connecting a fan
The AD9166 is a high-power device that can dissipate nearly 4W depending on the user application and configuration. Cooling requirements for EVAL-CN0511-RPIZ are high and the fan should always be on to regulate the temperature below 60 degrees Celsius.
Figure 9. Cooling Management Guide of CN0511
Connector P4 is the terminal block for optional external +5V input supply.
Example of System Setup
Figure 10. Overall System Setup Overview of CN0511
For the device to run, the SD card should have a preinstalled OS which is the Analog Devices Kuiper Linux, a distribution based on Raspbian for the Raspberry Pi.
It incorporates Linux device drivers for ADI products, and is created with ease of use in mind.
The reasoning behind creating this distribution is to minimize the barriers to integrating ADI hardware devices into a Linux-based system.
If a remote access in the device is required in an application, the CN0511 reference board connected to the can be remotely access by a remote PC either via LAN cable or via Wi-Fi.
Once the device has been setup, the generated Rfoutput from the CN0511 reference design can be viewed at its output terminal
Software Setup
Loading CN0511 Image on SD Card
In order to boot the RPi, obtain an SD card “image”, and write (or “burn”) it to a card. Refer to this guide for burning to a card: Burning SD Cards
- Download the compressed xz file, and extract the .img file. (tar.gz files can be extracted using 7zip in Windows.). You will need to install a separate software in order to flash the .img file into the SD card. The SD card image as well as a suggested etching software is available here: Kuiper Images.
- Use a 16GB or larger, high-quality, Class 10 or faster SD card.
- Follow the procedure for burning the SD card.
- Insert the burned SD card on the designated slot on RPi.
- The desktop with the industrial I/O (IIO) oscilloscope running should appear upon booting the RPi. In case the ADI IIO oscilloscope does not appear, it can be manually booted up under the Applications Menu (the first icon in the window header). Click on “Other” and you should be able to find the ADI IIO Oscilloscope.
Now, depending if you are using Linux or Windows, follow these instructions to write the file to your SD card.
Device Tree Overlay
For the Linux kernel to identify the device connected to the expansion header, update the device tree overlay. A Device Tree Overlay contains information about additional connected hardware, the EVAL-CN0511-RPIZ for this case. The overlay file is already included in the SD card and just needs to be matched to the EVAL-CN0511-RPIZ. With the RPi connected to the EVAL-CN0511-RPIZ and booted up, open a command prompt and type the commands shown in the next figures. The command prompt can be easily accessed using one of the icons in the window header. By default, it should be the fourth icon from the left of the window header.
analog@analog:~$ sudo nano /boot/config.txt
This will bring up the file in terminal. Scroll down until the line that begins with “dtoverlay” is found, then, whatever it currently is, change it to:
dtoverlay=rpi-cn0511
Save the file by Ctrl + X command. Reboot the system by typing on the command prompt:
analog@analog:~$ sudo reboot
Software
The RPI_demo_cn0511 provides a solution for controlling RF output power and tuning from DC up to 6GHz, using an EVAL-CN0511-RPIZ hat installed on an RPi base board. The user interface is implemented through wired and wireless connection.
Electronic Control and Diagnostics via IIO Oscilloscope
The EVAL-CN0511-RPIZ can be evaluated with the IIO Oscilloscope. Customers can use the CN0511 plugin tab, debug tab, and the DMM tab. Various controls and diagnostics are available in these plugins.
CN0511 IIO Oscilloscope Plugin
The CN0511 plugin tab provides a simple user interface to control the EVAL-CN0511-RPIZ as a signal generator.
Figure 11. Graphical User Interface (GUI) window of ADI IIO Oscilloscope with CN0511 Plugin
- Frequency Settings
- Sampling Frequency: Set desired DAC clock frequency here.
- NCO Settings
- NCO Frequency: Set the desired output signal frequency to be produced by the DAC.
- NCO Scale: Adjust the RF signal amplitude of the DAC output.
- Scale Calibration: Ramp down (or up) the full-scale current of the DAC RF signal output.
- DAC Amplifier
- Enable: Enable the DAC RF signal output.
Debug Tab
The debug tab provides direct access to IIO device and channel attributes as well as the registers of the CN0511 components. The IIO attributes and registers can be read and written for advanced configuration and information.
DMM Tab
The DMM tab provides temperature readings for ADF4372 and AD9166 using internal temperature sensors on both devices.
More Information and Useful Links
Schematic, PCB Layout, Bill of Materials
EVAL-CN0511-RPIZ Design & Integration Files
- Schematics
- PCB Layout
- Bill of Materials
- Allegro project
End of Document
resources/eval/user-guides/circuits-from-the-lab/cn0511.txt · Last modified: 27 May 2022 11:01 by erbe reyta