AD9434 no-OS Driver

See drivers/adc/ad9434 (doxygen) for the Doxygen documentation.

Supported Devices

• AD9434

Overview

The AD9434 is a 12-bit, 370 MSPS/500 MSPS analog-to-digital converter (ADC) designed for applications demanding high dynamic range and wide input bandwidth. Operating from a 1.8 V supply, it achieves an SNR of 65 dBFS and SFDR of 78 dBc at input frequencies up to 250 MHz at 500 MSPS. The device integrates a sample-and-hold circuit, an input buffer, and a voltage reference on-chip, requiring no external decoupling components. It features a 1 GHz full power analog bandwidth and a programmable input voltage range from 1.18 V p-p to 1.6 V p-p. Digital outputs are LVDS-compatible, supporting offset binary, twos complement, or Gray code formats. The AD9434 also includes a clock duty cycle stabilizer and an integrated data clock output with programmable clock and data alignment. Available in a 56-lead LFCSP, it is rated for the industrial temperature range of -40°C to +85°C.

Applications

• Wireless and wired broadband communications

• Cable reverse path

• Communications test equipment

• Radar and satellite subsystems

• Power amplifier linearization

Device Configuration

Driver Initialization

The ad9434_setup function initializes the AD9434 device. It allocates memory for an ad9434_dev structure, initializes SPI communication using the settings provided in the ad9434_init_param structure, and verifies the chip ID by reading the AD9434_REG_CHIP_ID register. If the ID does not match the expected AD9434_CHIP_ID, the function returns an error. Upon successful verification, the default output mode is configured using ad9434_outputmode_set.

SPI Communication

The driver communicates with the AD9434 over SPI using ad9434_spi_read and ad9434_spi_write. These functions handle low-level reading and writing of the ADC registers, constructing 3-byte SPI transactions with the register address and data.

Output Mode Configuration

The output data format can be configured using ad9434_outputmode_set, which writes the desired mode to the output mode register and triggers a transfer synchronization. Supported output formats include offset binary (OUTPUT_MODE_OFFSET_BINARY), twos complement (OUTPUT_MODE_TWOS_COMPLEMENT), and Gray code (OUTPUT_MODE_GRAY_CODE).

Test Mode Configuration

The ad9434_testmode_set function configures the ADC into various test modes for verification and debugging. Available test modes include midscale short (TESTMODE_MIDSCALE_SHORT), positive full-scale (TESTMODE_POS_FULLSCALE), negative full-scale (TESTMODE_NEG_FULLSCALE), alternating checkerboard (TESTMODE_ALT_CHECKERBOARD), PN23 sequence (TESTMODE_PN23_SEQ), PN9 sequence (TESTMODE_PN9_SEQ), one-zero toggle (TESTMODE_ONE_ZERO_TOGGLE), and user-defined (TESTMODE_USER_DEFINED).

Data Delay Adjustment

The ad9434_data_delay function adjusts the output data delay by writing to the AD9434_REG_OUTPUT_DELAY register and triggering a transfer synchronization. This enables fine-tuning of data timing to synchronize with other system components.

Driver Initialization Example

#include "ad9434.h"
#include "no_os_spi.h"

struct ad9434_dev *device;
int32_t ret;

struct ad9434_init_param init_param = {
    .spi_init = {
        .device_id    = SPI_DEVICE_ID,
        .max_speed_hz = 10000000,
        .chip_select  = SPI_CS,
        .mode         = NO_OS_SPI_MODE_0,
        .platform_ops = SPI_OPS,
        .extra        = SPI_EXTRA,
    }
};

ret = ad9434_setup(&device, init_param);
if (ret)
    goto error;