This version (15 Jun 2021 11:38) was approved by Michael Hennerich.

ADF4159 IIO Direct Modulation/Fast Waveform Generating Synthesizer Linux Driver

Supported Devices

Supported Boards

This driver supports the

Description

The ADF4159 is a 13 GHz, fractional-N frequency synthesizer with modulation and both fast and slow waveform generation capability. The part uses a 25-bit fixed modulus, allowing subhertz frequency resolution.

The ADF4159 consists of a low noise digital phase frequency detector (PFD), a precision charge pump, and a programmable reference divider. The Σ-Δ-based fractional interpolator allows programmable fractional-N division. The INT and FRAC registers define an overall N divider as N = INT + (FRAC/225).

The ADF4159 can be used to implement frequency shift keying (FSK) and phase shift keying (PSK) modulation. Frequency sweep modes are also available to generate various waveforms in the frequency domain, for example, sawtooth and triangular waveforms. Sweeps can be set to run automatically, or each step manually triggered by an external pulse. The ADF4159 features cycle slip reduction circuitry, which enables faster lock times without the need for modifications to the loop filter.

Control of all on-chip registers is via a simple 3-wire interface. The ADF4159 operates with an analog power supply in the range of 2.7 V to 3.45 V and a digital power supply in the range of 1.62 V to 1.98 V. The device can be powered down when not in use.

Applications

Communications infrastructure
Communications test equipment
Instrumentation
FMCW radars

Source Code

Status

Source	Mainlined?
drivers/iio/frequency/adf4159.c	WIP

Files

Function	File
driver	drivers/iio/frequency/adf4159.c
Documentation	adf4159.yaml
ABI documentation	sysfs-bus-iio-frequency-adf4159

Example device tree

Function	File
dts	rpi-adf4159-overlay.dts

Example platform device initialization

The adf4159 driver is a SPI bus driver and can be instantiated via device tree.

Required properties:

compatible: Should always be one of these:
- “adi,adf4159”
- “adi,adf4169”
reg: SPI chip select number.
spi-max-frequency: Max SPI frequency to use.
clocks: a list of phandle, one for each entry in clock-names.
clock-names: Must include the following entry: “clkin”

Example:

spi0 {
        #address-cells = <1>;
        #size-cells = <0>;
		adf4159@0 {
			compatible = "adi,adf4159";
			reg = <0x0>;
			spi-max-frequency = <12500000>;

			/* Clocks */
			clocks = <&clkin>;
			clock-names = "clkin";
			clock-output-names = "rf_out";
			#clock-cells = <0>;

			adi,power-up-frequency-hz = /bits/ 64 <6000000000>;
			adi,charge-pump-current-microamp = <900>;
			//adi,charge-pump-negative-bleed-enable;
			adi,clk1-div = <100>;
			adi,clk2-timer-div = <0>;
			adi,clk2-timer-div-2 = <0>;
			adi,clk-div-mode = <0>;
			//adi,cycle-slip-reduction-enable;
			//adi,delay-clk-sel-pfd-x-clk1-enable;
			//adi,delay-start-enable;
			adi,delay-start-word = <0>;
			adi,deviation = <1000>;
			adi,deviation-2 = <0>;
			adi,deviation-offset = <1>;
			//adi,dual-ramp-enable;
			//adi,fast-ramp-enable;
			//adi,fsk-modulation-enable;
			//adi,fsk-ramp-enable;
			adi,interrupt-mode-select = <0>;
			//adi,le-sync-refin-enable;
			//adi,lock-detect-precision-6ns-enable;
			adi,muxout-select = <MUXOUT_READBACK_TO_MUXOUT>;
			adi,negative-bleed-current-microamp = <0>;
			//adi,parabolic-ramp-enable;
			adi,phase = <0>;
			//adi,phase-detector-polarity-positive-enable;
			//adi,powerdown-enable;
			//adi,psk-modulation-enable;
			//adi,ramp-dealy-fl-enable;
			//adi,ramp-delay-enable;
			//adi,ramp-enable;
			adi,ramp-mode-select = <0>;
			adi,ramp-status-mode = <RAMP_STATUS_RAMP_COMPLETE_TO_MUXOUT>;
			//adi,reference-div2-enable;
			adi,reference-div-factor = <1>;
			//adi,reference-doubler-enable;
			//adi,single-full-triangle-enable;
			adi,step-word = <0>;
			adi,step-word-2 = <0>;
			//adi,txdata-invert-enable;
			//adi,txdata-ramp-clk-txdata-enable;
			//adi,txdata-trigger-delay-enable;
			//adi,txdata-trigger-enable;
		};

Enabling Linux driver support

Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)

The adf4159 driver depends on SPI and selects REGMAP_SPI

Adding Linux driver support

Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)

Linux Kernel Configuration
	Device Drivers  --->
	<*>     Industrial I/O support --->
	    --- Industrial I/O support
	             Frequency Synthesizers DDS/PLL --->
                             *** Phase-Locked Loop (PLL) frequency synthesizers ***
                             <*> Analog Devices ADF4159/ADF4169 Waveform Generating Synthesizers

Hardware configuration

Driver testing

Each and every IIO device, typically a hardware chip, has a device folder under /sys/bus/iio/devices/iio:deviceX. Where X is the IIO index of the device. Under every of these directory folders reside a set of files, depending on the characteristics and features of the hardware device in question. These files are consistently generalized and documented in the IIO ABI documentation. In order to determine which IIO deviceX corresponds to which hardware device, the user can read the name file /sys/bus/iio/devices/iio:deviceX/name. In case the sequence in which the iio device drivers are loaded/registered is constant, the numbering is constant and may be known in advance.

02 Mar 2011 15:16