ADF4159

ADF4159 IIO Direct Modulation/Fast Waveform Generating Synthesizer Linux Driver.

Supported Devices

• ADF4159

• ADF4169

Supported Boards

This driver supports the

• EV-ADF4159EB1Z

• EV-ADF4159EB3Z

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)

Note

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.

analog:/sys/bus/iio/devices/iio:device0# cd /sys/bus/iio/devices/
root@analog:/sys/bus/iio/devices# ls
iio:device0  iio:device1  iio:device2  iio:device3
root@analog:/sys/bus/iio/devices#

root@analog:/sys/bus/iio/devices# cd iio\:device0
root@analog:/sys/bus/iio/devices/iio:device1# ls -l
total 0
drwxr-xr-x 3 root root    0 Jan  1 00:00 .
drwxr-xr-x 5 root root    0 Jan  1 00:00 ..
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 dev
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 name
lrwxrwxrwx 1 root root    0 Jan  1 00:00 of_node -> ../../../../../../../../firmware/devicetree/base/amba/spi@e0007000/ad0
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 out_altvoltage0_frequency
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 out_altvoltage0_frequency_deviation_range
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 out_altvoltage0_frequency_deviation_step
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 out_altvoltage0_frequency_deviation_time
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 out_altvoltage0_powerdown
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 out_altvoltage0_ramp_mode
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 out_altvoltage_ramp_mode_available
drwxrwxrwx 2 root root    0 Jan  1 00:00 power
lrwxrwxrwx 1 root root    0 Jan  1 00:00 subsystem -> ../../../../../../../../bus/iio
-rw-rw-rw- 1 root root 4096 Jan  1 00:00 uevent
root@analog:/sys/bus/iio/devices/iio:device1#

Show device name

root@analog:/sys/bus/iio/devices/iio:device1# cat name
adf4159

Read output frequency

root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_frequency
6000000000

Set output frequency

Frequencies are in Hz

root@analog:/sys/bus/iio/devices/iio:device1# echo 6001000000 > out_altvoltage0_frequency
root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_frequency
6001000000

Output power down

root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_powerdown
0
root@analog:/sys/bus/iio/devices/iio:device1# echo 1 > out_altvoltage0_powerdown
root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_powerdown
1

Ramp modes

The ramp_mode attribute allows the user to control the output ramp mode of the chip. Valid values that can be written:

• disabled

• continuous_sawtooth

• continuous_triangular

• single_sawtooth_burst

• single_ramp_burst

root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage_ramp_mode_available
disabled continuous_sawtooth continuous_triangular single_sawtooth_burst single_ramp_burst
root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_ramp_mode
disabled
root@analog:/sys/bus/iio/devices/iio:device1# echo continuous_sawtooth > out_altvoltage0_ramp_mode
root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_ramp_mode
continuous_sawtooth

Ramp mode deviation step

This attribute sets the deviation_step in Hz. Values can be positive or negative. Negative values result in a ramp down.

root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_frequency_deviation_step
0
root@analog:/sys/bus/iio/devices/iio:device1# echo 1000 > out_altvoltage0_frequency_deviation_step
root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_frequency_deviation_step
998

Ramp mode deviation range

This attribute sets the deviation_range in Hz.

root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_frequency_deviation_range
0
root@analog:/sys/bus/iio/devices/iio:device1# echo 10000000 > out_altvoltage0_frequency_deviation_range
root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_frequency_deviation_range
9999960

Ramp mode deviation time

This attribute sets the deviation_time in us.

root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_frequency_deviation_time
0
root@analog:/sys/bus/iio/devices/iio:device1# echo 10000 > out_altvoltage0_frequency_deviation_time
root@analog:/sys/bus/iio/devices/iio:device1# cat out_altvoltage0_frequency_deviation_time
10020

Full device control via IIO debugfs

This device features an additional debugfs ABI, allowing the user to control additional features of the chip. Such as dual-ramp modes, muxout mappings, modulation features etc. All debugfs attributes have exactly the same naming as the devicetree attributes. So, for a complete description please see the devicetree property descriptions. In most cases these attributes correspond directly to bits and bitfields in the SPI register map. So, the ADF4159 datasheet should be consulted as well. Manipulating these debugfs attributes will not take effect unless at least one of the IIO device sysfs attributes is written/updated. For example, after setting adi,ramp-delay-enable write out_altvoltage0_powerdown afterwards, this flush all debugfs updates to the device.

root@analog:~# iio_attr -D adf4159
dev 'adf4159', debug attr 'adi,txdata-trigger-delay-enable', value :'N'
dev 'adf4159', debug attr 'adi,single-full-triangle-enable', value :'N'
dev 'adf4159', debug attr 'adi,txdata-trigger-enable', value :'N'
dev 'adf4159', debug attr 'adi,fast-ramp-enable', value :'N'
dev 'adf4159', debug attr 'adi,ramp-dealy-fl-enable', value :'N'
dev 'adf4159', debug attr 'adi,ramp-delay-enable', value :'N'
dev 'adf4159', debug attr 'adi,delay-clk-sel-pfd-x-clk1-enable', value :'N'
dev 'adf4159', debug attr 'adi,delay-start-enable', value :'N'
dev 'adf4159', debug attr 'adi,delay-start-word', value :'0'
dev 'adf4159', debug attr 'adi,step-word-2', value :'0'
dev 'adf4159', debug attr 'adi,step-word', value :'10020'
dev 'adf4159', debug attr 'adi,txdata-invert-enable', value :'N'
dev 'adf4159', debug attr 'adi,txdata-ramp-clk-txdata-enable', value :'N'
dev 'adf4159', debug attr 'adi,parabolic-ramp-enable', value :'N'
dev 'adf4159', debug attr 'adi,fsk-ramp-enable', value :'N'
dev 'adf4159', debug attr 'adi,dual-ramp-enable', value :'N'
dev 'adf4159', debug attr 'adi,interrupt-mode-select', value :'0'
dev 'adf4159', debug attr 'adi,deviation-offset', value :'0'
dev 'adf4159', debug attr 'adi,deviation-2', value :'0'
dev 'adf4159', debug attr 'adi,deviation', value :'335'
dev 'adf4159', debug attr 'adi,le-sync-refin-enable', value :'N'
dev 'adf4159', debug attr 'adi,ramp-status-mode', value :'3'
dev 'adf4159', debug attr 'adi,clk-div-mode', value :'0'
dev 'adf4159', debug attr 'adi,clk2-timer-div-2', value :'0'
dev 'adf4159', debug attr 'adi,clk2-timer-div', value :'100'
dev 'adf4159', debug attr 'adi,negative-bleed-current-microamp', value :'0'
dev 'adf4159', debug attr 'adi,ramp-mode-select', value :'0'
dev 'adf4159', debug attr 'adi,charge-pump-negative-bleed-enable', value :'N'
dev 'adf4159', debug attr 'adi,psk-modulation-enable', value :'N'
dev 'adf4159', debug attr 'adi,fsk-modulation-enable', value :'N'
dev 'adf4159', debug attr 'adi,lock-detect-precision-6ns-enable', value :'N'
dev 'adf4159', debug attr 'adi,phase-detector-polarity-positive-enable', value :'N'
dev 'adf4159', debug attr 'adi,powerdown-enable', value :'N'
dev 'adf4159', debug attr 'adi,cycle-slip-reduction-enable', value :'N'
dev 'adf4159', debug attr 'adi,reference-div2-enable', value :'N'
dev 'adf4159', debug attr 'adi,reference-doubler-enable', value :'N'
dev 'adf4159', debug attr 'adi,charge-pump-current-microamp', value :'900'
dev 'adf4159', debug attr 'adi,phase', value :'0'
dev 'adf4159', debug attr 'adi,ramp-enable', value :'N'
dev 'adf4159', debug attr 'adi,muxout-select', value :'15'
dev 'adf4159', debug attr 'adi,clkin-hz', value :'0'
dev 'adf4159', debug attr 'adi,clk1-div', value :'1'
dev 'adf4159', debug attr 'adi,reference-div-factor', value :'1'
dev 'adf4159', debug attr 'adi,frequency-deviation-time-us', value :'10000'
dev 'adf4159', debug attr 'adi,frequency-deviation-range-hz', value :'10000000'
dev 'adf4159', debug attr 'adi,frequency-deviation-step-hz', value :'1000'
dev 'adf4159', debug attr 'adi,power-up-frequency-hz', value :'6000000000'
dev 'adf4159', debug attr 'direct_reg_access', value :'0x781E0000'
root@analog:~#

Example:

root@analog:~# iio_attr -D adf4159 adi,ramp-delay-enable 1
Y
root@analog:~# iio_attr -c adf4159 altvoltage0 powerdown 0
0

More Information

• IIO mailing list: linux-iio@vger.kernel.org

• IIO Linux Kernel Documentation sysfs-bus-iio-*

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