MAX2201X no-OS Driver¶

Supported Devices¶

MAX22017 MAX22018

Overview¶

The MAX22017 is a two-channel industrial-grade configurable analog output device that can be changed on-the-fly in software to voltage or current output mode. The MAX22017 offers one 16-bit DAC per output channel. The MAX22017 can operate from an internal or external reference.

The MAX22018 is a single-channel industrial-grade configurable analog output device that can be changed on-the-fly in software to voltage or current output mode. The MAX22018 can operate from an internal or external reference. The MAX22018 features zero-drift high-voltage amplifiers and high voltage switches to be compliant with standard industrial-grade voltage and current ranges.

Both MAX22017 and MAX22018 have pretty much the same register map except channel’s 2 registers in case of MAX22018, therefor the max2201x.c and max2201x.h driver files support both devices.

MAX2201X Device Configuration¶

Driver Initialization¶

In order to be able to use the device, you will have to provide the support for the communication protocol (SPI) as well as an external GPIO for the RSTB pin.

The first API to be called is max2201x_init. Make sure that it returns 0, which means that the driver was intialized correctly.

GPIO Controller Configuration¶

Both devices have an internal GPIO controller, only difference is that MAX22017 supports 6 GPIOs meanwhile MAX22018 only supports 4 GPIOs. In the driver files the max2201x_gpio_ops can be found and used when declaring a no-OS GPIO initializaon parameter, therefor all the platform specific operation are called from the no-OS GPIO API as a standalone platform.

Channel Configuration¶

Channel data can be set/get with the max2201x_set_data and max2201x_get_data.

Channel slew-rate configuration can also be set using max2201x_slew_rate

Channel gain and offset can be calibrated with max2201x_offset_calib and max2201x_gain_calib.

Channel operation mode can also be configured using max2201x_op_mode as well as other channel specific configurations that can be changed using max2201x_config

Soft Reset¶

Both devices can be soft reseted by using max2201x_soft_reset.

MAX2201X Driver Initialization Example¶

struct max2201x_desc *max2201x;
struct no_os_spi_init_param spi_ip = {
        .device_id = 0,
        .extra = &max2201x_spi_extra,
        .max_speed_hz = 100000,
        .platform_ops = &max_spi_ops,
        .chip_select = 0,
};
struct no_os_gpio_init_param max2201x_rstb_ip = {
        .port = 1,
        .pull = NO_OS_PULL_NONE,
        .number = 6,
        .platform_ops = &max_gpio_ops,
        .extra = &max2201x_gpio_extra,
};
struct max2201x_init_param max2201x_ip = {
        .chip_id = ID_MAX22017,
        .comm_param = &max2201x_spi_ip,
        .crc_en = false,
        .ext_dac_ref = false,
        .rstb_param = &max2201x_rstb_ip,
};

ret = max2201x_init(&max2201x, &max2201x_ip);
if (ret)
        goto error;

MAX2201X no-OS IIO Support¶

The MAX2201X IIO driver comes on top of the MAX2201X driver and offers support for interfacing IIO clients through IIO lib.

MAX2201X IIO Device Configuration¶

Device Attributes¶

Channel Attributes¶

MAX2201X has a total of 2 channel attributes:

raw - the output data to be transmitted to the channel's DAC
offset - offset value used for channel's offset calibration

Debug Attributes¶

The device has a total of 37 debug attributes.

ow_detect - Open Wire detection status
ow_detect_available - List of possible options for Open Wire detection
timeout - Timeout value of the device
timeout_available - List of possible values for the timeout
timeout_cfg - Timeout Configuration
timeout_cfg_available - List of possible options for the timeout configuration
timeout_en - Timeout enable/disable
timeout_en_available - List of possible options for timeout status
thermal_shutdown - Thermal Shutdown status
thermal_shutdown_available - List of possible options for the thermal shutdown status
overcurrent_shutdown - Overcurrent Shutdown status
overcurrent_shutdown_available - List of possible options for the overcurrrent shutdown status
current_limit - Current Limit value
current_limit_available - List of possible values for current limit
dac_ref - DAC reference status
dac_ref_available - List of possible options for the DAC reference status
interrupts - Interrupts Word value
interrupts_enable - Interrups Enable Word value
ld_ctrl - Load DAC ctrl configuration
ld_ctrl_available - List of possible options for Load DAC ctrl configuration
gain - gain value used for channel's gain calibration
slew_rate - enable/disable slew rate
slew_rate_available - list of possible options for slew rate status
range - Channel's AO slew rate range
range_available - List of possible ranges depending on the application
step_size - Step size of the slew rate
step_size_available - list of possible values for the step size
update_rate - Update rate valuof the Channel's AO
update_rate_available - List of possible update rates
operation_mode - Operation mode of the channel
operation_mode_available - List of possible operation modes
polarity - Polarity of the channel
polarity_available - List of possible polarities
cm_sense - Common mode sense restistor value
cm_sense_available - List of possible values for the common mode resistor
ldac - Load DAC status
ldac - List of possible options for Load DAC status

Device Channels¶

MAX2201X has a specific API, max2201x_iio_setup_channels for configuring the channels at initialization depending on the chip id. Therefore the channels can be enabled/disabled only at initialization.

MAX2201X IIO Driver Initialization Example¶

int ret;

struct max2201x_iio_desc *max2201x_iio_desc;
struct max2201x_iio_desc_init_param max2201x_iio_ip = {
        .max2201x_init_param = &max2201x_ip,
};

struct iio_app_desc *app;
struct iio_app_init_param app_init_param = { 0 };

ret = max2201x_iio_init(&max2201x_iio_desc, &max2201x_iio_ip);
if (ret)
        goto error;

struct iio_app_device iio_devices[] = {
        {
                .name = "max2201x",
                .dev = max2201x_iio_desc,
                .dev_descriptor = max2201x_iio_desc->iio_dev,
        },
};

app_init_param.devices = iio_devices;
app_init_param.nb_devices = NO_OS_ARRAY_SIZE(iio_devices);
app_init_param.uart_init_params = max2201x_uart_ip;

ret = iio_app_init(&app, app_init_param);
if (ret)
        goto app_error;

return iio_app_run(app);