MAX22190 no-OS driver

Supported Devices

Overview

The MAX22190 is an IEC 61131-2 compliant industrial digital input device. The MAX22190 translates eight, 24V current-sinking, industrial inputs to a serialized SPI-compatible output that interfaces with 3V to 5.5V logic. A current setting resistor allows the MAX22190 to be configured for Type 1, Type 2, or Type 3 inputs. Field wiring is verified for proximity switches, by a second threshold detector on each input. When wire-break is enabled, the active-low FAULT output is asserted and a register flag is set if the input current drops below the wire-break threshold for more than 20ms. Additional diagnostics that assert the active-ow FAULT pin include: overtemperature, low 24V field supply, 24V field supply missing, CRC communication error, etc.

Applications

MAX22190

Building Automation
Industrial Automation
Process Automation
Programmable Logic Controllers

MAX22190 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).

The first API to be called is max22190_init. Make sure that it returns 0, which means that the driver was initialized correctly.

Channel Configuration

Each channel’s state can be set with the max22190_chan_state API. The user can also set a wire break detection for the channel with max22190_wbe_set API, and read the Wire Break state with max22190_wbe_get API.

Filter Configuration

Filter can be bypassed for each channel separately, although if they are not, the user can set a filter delay. All this can be done with the max22190_filter_set API, and also the user can read the filter configuration for each channel with max22190_filter_get.

Fault Enable Configuration

Fault Enable bits can be configured with the help of the max22190_fault_enable_set API and read with max22190_fault_enable_get. If an enable bit is set, then the fault will be signaled in the fault register, otherwise it will not.

MAX22190 Driver Initialization Example

struct max22190_desc *max22190_desc;
struct no_os_spi_init_param max22190_spi_ip = {
        .device_id = 0,
        .extra = &max22190_spi_extra,
        .max_speed_hz = 100000,
        .platform_ops = &max_spi_ops,
        .chip_select = 1,
};
struct max22190_init_param max22190_ip = {
        .comm_param = &max22190_spi_ip,
        .crc_en = false,
};
ret = max22190_init(&max22190_desc, &max22190_ip);
if (ret)
        goto error;

MAX22190 no-OS IIO support

The MAX22190 IIO driver comes on top of the MAX22190 driver and offers support for interfacing IIO clients through libiio.

MAX22190 IIO Device Configuration

Channel Attributes

MAX22190 has a total of 6 channel attributes:

raw - the state of a channel
offset - always 0
scale - always 1
filter_bypass - determines if the filter is used on the requested channel or not.
filter_delay - if the filter_bypass is set to 1, the filter's delay can be set from here.
filter_delay_available - list of possible filter delay's.

Debug Attributes

fault1 - fault1 register value

fault2 - fault2 register value

wbg_enable - Wire Break detection asserted to fault pin

24vm_enable - 24V Supply Missing detection asserted to fault pin

24vl_enable - 24V Supply Low detection asserted to fault pin

alrmt1_enable - Alarm 1 threshold detection asserted to fault pin

alrmt2_enable - Alarm 2 threshold detection asserted to fault pin

fault2_enable - Any bit from fault2 is asserted to fault pin

rfwbs_enable - RFWB short detection is asserted to fault pin

rfwbo_enable - RFWB open detection is asserted to fault pin

rfdis_enable - RFDI short detection is asserted to fault pin

rfdio_enable - RFDI open detection is asserted to fault pin

otshdn_enable - Overtemperature shutdown

fault8ck_enable - SPI receives bad number of clock pulses

Device Channels

MAX22190 has a specific API, max22190_iio_setup_channels for configuring the channels at the initialization, therefore the channels can be enabled or disabled at initialization only.

MAX22190 IIO Driver Initialization Example

int ret;

struct max22190_iio_desc *max22190_iio_desc;
struct max22190_iio_desc_init_param max22190_iio_ip = {
        .max22190_init_param = &max22190_ip,
        .ch_enabled = {
                true, true, true, false, false, false, false, false
        },
};

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

ret = max22190_iio_init(&max22190_iio_desc, &max22190_iio_ip);
if (ret)
        goto error;

struct iio_app_device iio_devices[] = {
        {
                .name = "max22190",
                .dev = max22190_iio_desc,
                .dev_descriptor = max22190_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 = max22190_uart_ip;

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

return iio_app_run(app);