AD9144 no-OS Driver

See drivers/dac/ad9144 (doxygen) for the Doxygen documentation.

Supported Devices

AD9144

Overview

The AD9144 is a quad, 16-bit, 2.8 GSPS digital-to-analog converter (DAC) designed to generate multicarrier signals up to the Nyquist frequency. It interfaces seamlessly with the ADRF6720 analog quadrature modulator from Analog Devices. The device features a JESD204B Subclass 1 serial data interface with up to eight lanes, reducing the required pin count while enabling synchronized multichip operation. The DAC output current is programmable between 13.9 mA and 27.0 mA. Additional features include 3-wire and 4-wire SPI support, a programmable transmit enable function for optimizing power consumption and wake-up time, and an internal PLL for flexible clocking. The AD9144 is housed in an 88-lead LFCSP package.

Applications

3G/4G W-CDMA base stations
Wideband repeaters
Software defined radios
Point-to-point communications
Local multipoint distribution service (LMDS) and multichannel multipoint distribution service (MMDS)
Transmit diversity and MIMO
Instrumentation
Automated test equipment

Device Configuration

Initialization and Setup

The driver provides two initialization paths. The ad9144_setup_legacy function initializes the device without the JESD204 finite state machine, while ad9144_setup_jesd_fsm initializes the device with JESD204 FSM support for automated link bring-up. Both functions accept an ad9144_init_param structure containing SPI configuration, JESD204B link parameters, converter/lane counts, interpolation settings, and PLL configuration.

SPI Communication

The AD9144 uses SPI for register access. The driver provides ad9144_spi_read for reading register values, ad9144_spi_write for writing register values, and ad9144_spi_check_status for verifying that a register field matches an expected value.

JESD204B Link Configuration

The JESD204B link is configured during initialization via the ad9144_setup_jesd204_link function, which sets up the link parameters including the number of converters, lanes, samples per frame, and octets per frame based on the selected JESD204B mode. The device supports multiple link modes with varying combinations of converters (1, 2, or 4), lanes (1 to 8), and framing options.

NCO Configuration

The ad9144_set_nco function configures the numerically controlled oscillator, allowing the user to set a carrier frequency offset (in kHz) and phase for the DAC output signal.

Testing and Calibration

The driver includes ad9144_dac_calibrate for DAC calibration, ad9144_short_pattern_test for verifying JESD204B short transport layer pattern data, and ad9144_datapath_prbs_test for pseudo-random bit sequence testing of the data path.

Status and Cleanup

The ad9144_status function retrieves the operational status of the device, including lane and link synchronization state. The ad9144_remove function releases all allocated resources associated with the device.

Driver Initialization Example

#include "ad9144.h"

struct ad9144_init_param init_param = {
    .spi_init = {
        .device_id       = SPI_DEVICE_ID,
        .max_speed_hz    = 1000000,
        .chip_select     = SPI_AD9144_CS,
        .mode            = NO_OS_SPI_MODE_0,
        .platform_ops    = &xil_spi_ops,
        .extra           = &xil_spi_init_param,
    },
    .spi3wire            = 0,
    .num_converters      = 4,
    .num_lanes           = 8,
    .interpolation       = 2,
    .fcenter_shift       = 0,
    .stpl_samples        = { { 0x1111, 0x2222, 0x3333, 0x4444 },
                             { 0x5555, 0x6666, 0x7777, 0x8888 },
                             { 0x9999, 0xAAAA, 0xBBBB, 0xCCCC },
                             { 0xDDDD, 0xEEEE, 0xFFFF, 0x0000 } },
    .lane_rate_kbps      = 5000000,
    .prbs_type           = 0,
    .jesd204_mode        = 0,
    .jesd204_subclass    = 1,
    .jesd204_scrambling  = 1,
    .lane_mux            = { 0, 1, 2, 3, 4, 5, 6, 7 },
    .pll_enable          = 1,
    .pll_ref_frequency_khz = 50000,
    .pll_dac_frequency_khz = 1000000,
};

struct ad9144_dev *dev;
int32_t ret;

ret = ad9144_setup_legacy(&dev, &init_param);
if (ret)
    goto error;