Linux User Guide

This guide uses Linux and supports the Digilent Cora Z7S and Terasic DE10-Nano carriers. For bare-metal evaluation, see No-OS User Guide.

Before you begin

Prepare an SD card by following the Kuiper Linux documentation. The AD4062 driver is available in both the upstream Linux kernel and the ADI Linux fork, including the Kuiper release images. You can always use a custom kernel and HDL build as described in Flashing the firmware to tinker with the stack.

Devicetree

Because I3C is a discoverable protocol, the ADC device tree node is optional. If you add one, follow Documentation/devicetree/bindings/iio/adc/adi%2Cad4062.yaml.

For the HDL I3C controller, see Documentation/devicetree/bindings/i3c/adi,i3c-master.yaml and I3C Controller.

Hardware setup

After preparing the Linux SD card, set up the hardware as follows:

• Disconnect both the evaluation board and the carrier from all power sources.

• Add the SD Card to the carrier.

• Connect the evaluation board to the carrier through the Arduino Uno compatible headers. There is only one orientation in which all pins mate.

• Check the carrier-specific jumper and power instructions.

• When powering the evaluation board from the carrier, follow:

  • Set JP2 jumper on the evaluation board to the +5V position. This position connects the evaluation board power management circuitry to the +5 V pin on the Arduino Uno power header.

  • Connect the carrier to a PC with a USB cable, the evaluation board DS1 LED should turn on, as well as other LEDs on the carrier.

• When powering the evaluation board from an external power supply, follow:

  • Set JP2 jumper on the evaluation board to the VIN position. This position connects the evaluation board power management circuitry to the VIN pin on the Arduino Uno power header.

  • Power on the carrier via the external power supply option (in general, via a DC jack), the evaluation board DS1 LED should turn on, as well as other LEDs on the carrier.

  • Connect the carrier to a PC with a USB cable.

I3C Address Configuration

The AD4060/AD4062 include three digital input pins ADDR0, ADDR1, and ADDR2. The ADDR[2:0] pins enable the assignment of up to eight unique part instance values to support up to eight AD4060/AD4062s on one I3C bus.

The evaluation board’s jumpers JP11, JP12, and JP10 allow for setting the ADDR0, ADDR1, and ADDR2 respectively to either VIO or GND.

Flashing the firmware

Perform these steps with the carrier powered off.

For either carrier, prepare an SD card with Kuiper Linux.

You can also build a custom kernel and HDL image as described in the Linux kernel build guide and HDL build guide.

Insert the SD card into the powered-off carrier, then complete the hardware setup steps.

Quick start

Connect a precision signal source or signal generator to the analog input Subminiature Version A (SMA) connectors to drive the AD4060/AD4062 inputs into their specified operating ranges.

Figure 1 Biasing the EVAL-AD4062-ARDZ Inputs Without Signal Generator Hardware for Software Validation

If no signal generator is available, a jumper cable between the VREF and VCM test points can be used to bias the AD4060/ AD4062 analog inputs to VREF. This is preferred over connecting the amplifier inputs to GND, because the amplifier VEE rails are connected to GND by default.

Evaluation board hardware

The evaluation board includes the AD4060/AD4062 with companion circuitry for an out-of-the-box evaluation experience:

• ADC: AD4060BCPZ/AD4062BCPZ (14-lead LFCSP)

• Voltage reference: MAX6070 2.5V low-noise reference

• Amplifiers: Two MAX44260 low-power, rail-to-rail op amps

• Power regulator: ADP7118 3.3V LDO regulator

Digital Interface

The AD4060/AD4062 digital interface includes:

• I3C bus: For reading and writing data (SDA and SCL on Arduino headers)

• GP0/GP1: Two programmable GPIOs with multiple functions:

  • Data Ready (RDY) signal

  • Threshold interrupt (GP_INTR)

  • Device enable (DEV_EN) for AFE power cycling

  • Static high/low outputs

  • GPIO controller functionality (Linux only)

• EEPROM: On-board I2C EEPROM for board identification

Power Domains

The evaluation board operates on the following power domains:

Power Rail	Source	Default Voltage
+5V/VIN	Arduino header (from carrier)	5V
VSUPPLY	ADP7118 LDO regulator	3.3V
VDD	VSUPPLY (via JP8)	3.3V
VIO	IOREF from carrier (via JP1)	3.3V
VREF	MAX6070 reference	2.5V

For more detailed hardware information, see the EVAL-AD4060/AD4062 User Guide.

Interfacing with IIO

The Linux IIO driver provides a complete feature set for the AD4060/AD4062, including threshold events, triggers, and GPIO controller support.

For language bindings and high level GUI tools see Libraries and GUI Tools.

Device enumeration

On the carrier Linux shell:

~$

iio_info

Or from a host PC via Ethernet:

~$

iio_info -u ip:192.168.2.1

The device appears as ad4062 or ad4060 depending on the part.

Available channels

The Linux driver exposes a single channel:

• voltage0: Differential voltage input channel

Channel attributes

The channel provides the following standard IIO attributes:

Attribute	Access	Description
raw	Read	Raw ADC value
scale	Read	Scale factor to convert raw to mV (based on VREF)
calibscale	Read/Write	Hardware gain calibration factor
oversampling_ratio	Read/Write	Burst averaging ratio (1, 2, 4, 8, 16, …)
oversampling_ratio_available	Read	List of supported oversampling ratios
sampling_frequency	Read/Write	Effective sampling frequency in Hz
sampling_frequency_available	Read	List of available sampling frequencies

Reading voltage

Read the raw ADC value:

~$

iio_attr -c ad4062 voltage0 raw

Read the scale factor:

~$

iio_attr -c ad4062 voltage0 scale

Calculate the voltage in mV: voltage_mV = raw * scale

Configuring oversampling

View available oversampling ratios:

~$

iio_attr -c ad4062 voltage0 oversampling_ratio_available

Set oversampling ratio (value 1 disables oversampling):

~$

iio_attr -c ad4062 voltage0 oversampling_ratio 8

Note

When oversampling is enabled (ratio > 1), the device enters burst averaging mode, which increases the resolution but reduces the effective sample rate.

Configuring sampling frequency

View available sampling frequencies for the current oversampling ratio:

~$

iio_attr -c ad4062 voltage0 sampling_frequency_available

Set the sampling frequency:

~$

iio_attr -c ad4062 voltage0 sampling_frequency 1000000

Note

The available sampling frequencies depend on the current oversampling ratio. Changing the oversampling ratio will update the list of available frequencies.

Hardware gain calibration

The device supports hardware gain calibration to compensate for system gain errors:

# Read current calibration scale

~$

iio_attr -c ad4062 voltage0 calibscale

# Set calibration scale (normalized value)

~$

iio_attr -c ad4062 voltage0 calibscale 1.005

IIO buffered data capture

The Linux driver supports buffered data acquisition using IIO triggers.

Attach the trigger

The driver automatically registers a trigger named ad4062-dev0 (or similar). Before enabling the buffer, attach the trigger:

# Find the trigger name

~$

ls /sys/bus/iio/devices/trigger*/name

# Set the current trigger

~$

echo ad4062-dev0 > /sys/bus/iio/devices/iio:device0/trigger/current_trigger

Enable the buffer

# Enable the channel for buffered capture

~$

echo 1 > /sys/bus/iio/devices/iio:device0/scan_elements/in_voltage0_en

# Set the buffer size

~$

echo 256 > /sys/bus/iio/devices/iio:device0/buffer/length

# Enable the buffer

~$

echo 1 > /sys/bus/iio/devices/iio:device0/buffer/enable

Read buffered data

Using iio_readdev:

~$

iio_readdev -s 1024 -b 256 ad4062 voltage0 > data.bin

Important

The trigger must be attached before enabling the buffer, otherwise the buffer will not capture data.

Threshold event monitoring

The AD4060/AD4062 support autonomous threshold monitoring. When enabled, the device continuously samples and compares the result against programmable thresholds, generating an event when the threshold is crossed.

Note

During threshold monitoring (monitor mode), the device operates autonomously. Any register access temporarily exits monitor mode. The Linux driver manages this automatically.

Event attributes

Threshold events are configured through event attributes under the channel:

# List event attributes

~$

ls /sys/bus/iio/devices/iio:device0/events/

Available event attributes:

Attribute	Access	Description
in_voltage0_thresh_either_en	Read/Write	Enable threshold monitoring (0=disabled, 1=enabled)
in_voltage0_thresh_rising_value	Read/Write	Upper threshold value (raw ADC counts)
in_voltage0_thresh_rising_hysteresis	Read/Write	Hysteresis for upper threshold
in_voltage0_thresh_falling_value	Read/Write	Lower threshold value (raw ADC counts)
in_voltage0_thresh_falling_hysteresis	Read/Write	Hysteresis for lower threshold
sampling_frequency	Read/Write	Sampling frequency during monitor mode
sampling_frequency_available	Read	List of available monitor mode frequencies

Setting thresholds

# Set upper threshold (rising)

~$

iio_attr -c ad4062 voltage0 events/thresh_rising_value 30000

# Set upper threshold hysteresis

~$

iio_attr -c ad4062 voltage0 events/thresh_rising_hysteresis 500

# Set lower threshold (falling)

~$

iio_attr -c ad4062 voltage0 events/thresh_falling_value 10000

# Set lower threshold hysteresis

~$

iio_attr -c ad4062 voltage0 events/thresh_falling_hysteresis 500

Configuring monitor mode sampling frequency

# View available frequencies

~$

iio_attr -c ad4062 voltage0 events/sampling_frequency_available

# Set monitor mode frequency

~$

iio_attr -c ad4062 voltage0 events/sampling_frequency 100000

Enabling threshold monitoring

# Enable threshold monitoring

~$

iio_attr -c ad4062 voltage0 events/thresh_either_en 1

# Disable threshold monitoring

~$

iio_attr -c ad4062 voltage0 events/thresh_either_en 0

Reading events

Events can be read from the character device:

# Monitor events (blocking read)

~$

cat /dev/iio:device0

Or use iio_event_monitor if available:

~$

iio_event_monitor ad4062

Important

While threshold monitoring is enabled, normal ADC reads are not available. Disable monitoring to return to regular sampling mode.

GPIO controller

When configured in the device tree, GP0 and GP1 are exposed through the GPIO character-device interface as general-purpose outputs.

Device tree configuration

To enable GPIO controller support, add the gpio-controller property to the device node in the device tree:

&i3c0 {
    adc@0,2ee007c0000 {
        compatible = "adi,ad4062";
        reg = <0x0 0x2ee 0x7c0000>;
        vdd-supply = <&vdd>;
        vio-supply = <&vio>;
        ref-supply = <&ref>;

        gpio-controller;
        #gpio-cells = <2>;
    };
};

GPIO indexing

The GPIO indices match the physical pin numbers:

• GPIO 0 = GP0

• GPIO 1 = GP1

If a GP pin is configured as an interrupt in the interrupt-names property, it is not available as a GPIO.

Using GPIOs from userspace

Use gpiodetect to identify the gpiochip labeled ad4062 (or ad4060), then use gpioset from libgpiod to drive a line. For example, to set GP1 (line 1) high:

~$

gpiodetect

~$

gpioset gpiochip0 1=1

The gpiochip number depends on the system. See the GPIO character device userspace API for more details.

Low-power mode

The Linux driver automatically manages low-power mode. When the device is idle (not actively sampling), it enters low-power mode to reduce power consumption.

Threshold event monitoring disables low-power mode, as the device must continuously sample to detect threshold crossings.

References

• AD4060 Product Page

• AD4062 Product Page

• AD4060 Datasheet

• AD4062 Datasheet

• EVAL-AD4060-ARDZ Product Page

• EVAL-AD4062-ARDZ Product Page

• Evaluation Guide (UG-2318)

• HDL Project Documentation

• Linux Driver Source

• Linux Driver Documentation

• Linux Devicetree Bindings

• no-OS Driver Documentation

• no-OS Project Documentation