AD4630-FMC HDL project#

Overview#

The AD4630-24 is a two-channel, simultaneous sampling, Easy Drive, 2 MSPS successive approximation register (SAR) analog-to-digital converter (ADC). The AD4030-24 is the single channel version. With a guaranteed maximum ±0.9 ppm INL and no missing codes at 24-bits, the AD4630-24 and AD4030-24 achieve unparalleled precision from −40°C to +125°C. The AD4030-16 is a 16-bit dual channel version.

A low-drift, internal precision reference buffer eases voltage reference sharing with other system circuitry. The AD4630-24 offers a typical dynamic range of 106 dB when using a 5 V reference. The AD4030-24 offers a typical dynamic range of 109 dB using a 5 V reference. The low noise floor enables signal chains requiring less gain and lower power. A block averaging filter with programmable decimation ratio can increase dynamic range up to 153 dB and 155.5dB for the AD4030. The wide differential input and common mode ranges allow inputs to use the full ±VREF range without saturating, simplifying signal conditioning requirements and system calibration. The improved settling of the Easy Drive analog inputs broadens the selection of analog front-end components compatible with the AD4630-24, AD4630-16 and AD4030-24. Both single-ended and differential signals are supported.

The versatile Flexi-SPI serial interface eases host processor and ADC integration. A wide data clocking window, multiple SDO lanes, and optional DDR data clocking can reduce the serial clock to 10 MHz while operating at a sample rate of 2 MSPS. Echo clock mode and ADC master clock mode relax the timing requirements and simplify the use of digital isolators.

The AD4630-24’s, AD4630-16’s and AD4030-24’s BGA package integrates all critical power supply and reference bypass capacitors, reducing the footprint and system component count, and lessening sensitivity to board layout.

The ADAQ4224 is a μModule® precision data acquisition (DAQ) signal chain solution that reduces the development cycle of a precision measurement system by transferring the signal chain design challenge of component selection, optimization, and layout from the designer to the device. With a guaranteed maximum ±TBD ppm INL and no missing codes at 24 bits, the ADAQ4224 achieves unparalleled precision from −40°C to +85°C.

The HDL reference design for the EVAL-AD4630_FMCZ and EVAL-AD4030_FMCZ provides all the interfaces that are necessary to interact with the device using a Xilinx FPGA development board. The design has all the necessary infrastructure to acquire data from the AD4630-24 24-bit dual-channel precision SAR ADC, AD4630-16 16-bit dual channel precision SAR ADC and AD4030-24 single channel ADC, supporting continuous data capture at maximum 2 MSPS data rate. The design targeted to the Zedboard, which is a low cost FPGA carrier board from Digilent, using a Zynq-7000 re-programmable SoC from Xilinx.

Applications:

  • Automatic test equipment

  • Digital control loops

  • Medical instrumentation

  • Seismology

  • Semiconductor manufacturing

  • Scientific instrumentation

Supported boards#

Supported devices#

Supported carriers#

Block design#

The reference design uses the SPI Engine Framework to interface with the AD4630 ADC. The design supports almost all possible digital interface configurations of the device. In echo clock mode, because the clock for data latching is routed back through the BUSY line, an additional data capture module is used for saving the received samples and transmitting forward for the DMA.

There are three modes in which the system can run. Refer to the AD4630-24, AD4630-16 or AD4030-24 data sheet section titled SAMPLE CONVERSION TIMING AND DATA TRANSFER for more explanation of data transfer zones.

Block diagram#

The data path and clock domains are depicted in the below diagrams:

SPI mode - transfer zone 1#

The main aspect of this mode is the fact that it is using the BUSY signal from the ADC to trigger the Offload module. Data is then clocked out by the Execution module and transferred to the DMA by the Offload module. CNV is always generated by the AXI PWM GEN IP core regardless of the mode. Zone 1 transfer is not currently supported by the pre-compiled HDL files that are included in the SD card image that is provided with the evaluation board.

AD4630_FMC SPI mode - transfer zone 1 block diagram

SPI mode - transfer zone 2#

In this mode, the BUSY signal is not used and both the CNV and the Offload trigger signals are generated by the AXI PWM GEN core. The reason for using two PWM outputs instead of a common one is to accommodate for the averaging mode where the two signals will have different frequencies.

AD4630_FMC SPI mode - transfer zone 2 block diagram ADAQ4224_FMC SPI mode - transfer zone 2 block diagram

Echo clock mode - transfer zone 2#

In this configuration, the ADC’s BUSY-SCKOUT pin functions as a bit-clock output and is generated by looping-through the host’s SCK. The SPI engine is driving the SPI signals except it is no longer reading the data. For this purpose, the Data Capture IP is used. This also allows for reading data in DDR mode.

AD4630_FMC Echo clock mode - transfer zone 2 block diagram ADAQ4224_FMC Echo clock mode - transfer zone 2 block diagram

The design supports the following interface and clock modes both in SDR and DDR:

Mode

1 Lane per channel

2 Lane per channel

4 lane per channel

SPI mode

yes

yes

yes

Echo Clock mode

yes

yes

yes

Configuration modes#

The CLK_MODE configuration parameter defines clocking mode of the device’s digital interface: Options: 0 - SPI mode, 1 - Echo-clock or Master clock mode

The NUM_OF_SDI configutation parameter defines the number of MOSI lines of the SPI interface: Options: 1 - Interleaved mode, 2 - 1 lane per channel, 4 - 2 lanes per channel, 8 - 4 lanes per channel

The CAPTURE_ZONE configuration parameter defines the capture zone of the next sample. There are two capture zones: 1 - from negative edge of the BUSY line until the next CNV positive edge -20ns, 2 - from the next consecutive CNV positive edge +20ns until the second next consecutive CNV positive edge -20ns

The DDR_EN configuration parameter defines the type of data transfer. In echo and master clock mode the SDI lines can have Single or Double Data Rates. Options: 0 - MISO runs on SDR, 1 - MISO runs on DDR.

CPU/Memory interconnects addresses#

The addresses are dependent on the architecture of the FPGA, having an offset added to the base address from HDL(see more at HDL Architecture).

Instance

Address

spi_ad463x_axi_regmap

0x44A0_0000

axi_ad463x_dma

0x44A3_0000

spi_clkgen

0x44A7_0000

cnv_generator

0x44B0_0000

sync_generator*

0x44C0_0000

Legend

  • * instantiated, but only used for ADAQ4224 with isolated power supply

I2C connections#

I2C type

I2C manager instance

Alias

Address

I2C subordinate

PL

iic_fmc

axi_iic_fmc

0x4162_0000

—

0x50

eeprom

0x5F

temperature sensor *

Legend

  • * Temperature Sensor HW Monitor is present only in ADAQ4224

SPI connections#

SPI type

SPI manager instance

SPI subordinate

CS

PL

axi_spi_engine

ad4630

0

GPIOs#

The Software GPIO number is calculated as follows:

  • Zynq-7000: if PS7 is used, then offset is 54

GPIO signal

Direction

HDL GPIO EMIO

Software GPIO

(from FPGA view)

Zynq-7000

ad463x_resetn

INOUT

32

86

adaq42xx_pgia_mux[0]*

INOUT

33

87

adaq42xx_pgia_mux[1]*

INOUT

34

88

max17687_rst**

INOUT

35

89

Legend

  • * instantiated, but used for ADAQ4224 only

  • ** instantiated, but used for ADAQ4224 with isolated power supply

Interrupts#

Below are the Programmable Logic interrupts used in this project.

Instance name

HDL

Linux Zynq

Actual Zynq

axi_ad463x_dma

13

57

89

spi_ad463x

12

56

88

Building the HDL project#

The design is built upon ADI’s generic HDL reference design framework. ADI does not distribute the bit/elf files of these projects so they must be built from the sources available here. To get the source you must clone the HDL repository, and then build the project as follows:.

Linux/Cygwin/WSL

1user@analog:~$ cd hdl/projects/ad4630_fmc/zed
2user@analog:~/hdl/projects/ad4630_fmc/zed$ make NUM_OF_SDI=4 CAPTURE_ZONE=2

The result of the build, if parameters were used, will be in a folder named by the configuration used:

if the following command was run

make NUM_OF_SDI=4 CAPTURE_ZONE=2

then the folder name will be:

NUMOFSDI4_CAPTUREZONE2

A more comprehensive build guide can be found in the Build an HDL project user guide.

Resources#

More information#

Support#

Analog Devices, Inc. will provide limited online support for anyone using the reference design with ADI components via the EngineerZone FPGA reference designs forum.

For questions regarding the ADI Linux device drivers, device trees, etc. from our Linux GitHub repository, the team will offer support on the EngineerZone Linux software drivers forum.

For questions concerning the ADI No-OS drivers, from our No-OS GitHub repository, the team will offer support on the EngineerZone microcontroller No-OS drivers forum.

It should be noted, that the older the tools’ versions and release branches are, the lower the chances to receive support from ADI engineers.