• ADIS16375
• ADIS16480
• ADIS16485
• ADIS16488
• ADIS16490
• ADIS16495
• ADIS16497

• ADIS16IMU1/PCBZ

This is a Linux industrial I/O (IIO) subsystem driver, targeting serial interface Inertial Measurement Units (IMU). The industrial I/O subsystem provides a unified framework for drivers for many different types of converters and sensors using a number of different physical interfaces (i2c, spi, etc). See IIO for more information.

Depending on the converter IC used, you may need to set the modalias accordingly, matching your part name. It may also required to adjust max_speed_hz. Please consult the datasheet, for maximum spi clock supported by the device in question.

static struct spi_board_info board_spi_board_info[] __initdata = {
#if defined(CONFIG_adis16480) /
	|| defined(CONFIG_adis16480_MODULE)
	{
		.modalias = "adis16480",
		.max_speed_hz = 2000000,     /* max spi clock (SCK) speed in HZ */
		.bus_num = 0,
		.chip_select = 1, /* CS, change it for your board */
		.platform_data = NULL, /* No spi_driver specific config */
		.mode = SPI_MODE_3,
		.irq = IRQ_PF5,
	},
#endif
 
};

static int __init board_init(void)
{
	[--snip--]
 
	spi_register_board_info(board_spi_board_info, ARRAY_SIZE(board_spi_board_info));
 
	[--snip--]
 
	return 0;
}
arch_initcall(board_init);

Analog Devices ADIS16480 and similar IMUs

• compatible: Must be one of
  • “adi,adis16375”
  • “adi,adis16480”
  • “adi,adis16485”
  • “adi,adis16488”
  • “adi,adis16490”
  • “adi,adis16495-1”
  • “adi,adis16495-2”
  • “adi,adis16495-3”
  • “adi,adis16497-1”
  • “adi,adis16497-2”
  • “adi,adis16497-3”

• reg: SPI chip select number for the device
• spi-max-frequency: Max SPI frequency to use see: Documentation/devicetree/bindings/spi/spi-bus.txt
• spi-cpha: See Documentation/devicetree/bindings/spi/spi-bus.txt
• spi-cpol: See Documentation/devicetree/bindings/spi/spi-bus.txt
• interrupts: interrupt mapping for IRQ, accepted values are:
• IRQF_TRIGGER_RISING
• IRQF_TRIGGER_FALLING

• interrupt-names: Data ready line selection. Valid values are:

If this field is left empty, the factory default assigns DIO2 as data ready signal.

• DIO1
• DIO2
• DIO3
• DIO4

• reset-gpios: must be the device tree identifier of the RESET pin. As the line is active low, it should be marked GPIO_ACTIVE_LOW.

• clocks: phandle to the external clock. Should be set according to “clock-names”. If this field is left empty, the internal clock is used.
• clock-names: The name of the external clock to be used. Valid values are:
• sync: In sync mode, the internal clock is disabled and the frequency of the external clock signal establishes the rate of data collection and processing. The clock-frequency must be:
  • 3000 to 4500 Hz for adis1649x devices.
  • 700 to 2400 Hz for adis1648x devices.
• pps: In Pulse Per Second (PPS) Mode, the rate of data collection and production is equal to the product of the external clock frequency and the scale factor in the SYNC_SCALE register, see Table 154 in the datasheet. The clock-frequency must be:
  • 1 to 128 Hz for adis1649x devices.
  • This mode is not supported by adis1648x devices.

If this field is left empty, the internal clock is used.

• adi,ext-clk-pin: The DIOx line to be used as an external clock input. Valid values are:
• DIO1
• DIO2
• DIO3
• DIO4

Each DIOx pin supports only one function at a time (data ready line selection or external clock input). When a single pin has two assignments, the enable bit for the lower priority function automatically resets to zero (disabling the lower priority function). Data ready has highest priority. If this field is left empty, DIO2 is assigned as default external clock input pin.

	imu@0 {
		compatible = "adi,adis16495-1";
		reg = <0>;
		spi-max-frequency = <3200000>;
		spi-cpol;
		spi-cpha;
		interrupts = <25 IRQF_TRIGGER_FALLING>;
		interrupt-parent = <&gpio>;
		interrupt-names = "DIO2";
		clocks = <&adis16495_sync>;
		clock-names = "sync";
		adi,ext-clk-pin = "DIO1";
       };

Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)

Linux Kernel Configuration
	Device Drivers  --->
		<*>     Industrial I/O support --->
			--- Industrial I/O support
			[*]   Enable buffer support within IIO
			-*-     Industrial I/O buffering based on kfifo
			-*-   Enable triggered sampling support
			[--snip--]
			Inertial measurement units  ---> 
				[--snip--]
				<*> Analog Devices ADIS16480 and similar IMU driver
				[--snip--]

The ADIS16IMU1/PCBZ is the primary breakout board for the ADIS1649x products. This breakout board simplifies the process of connecting an ADIS1649x IMU to an embedded processor system using a 16-pin, 1mm ribbon cable. For a detailed description, please see: adis1649x Here is an example of basic connection from the ADIS1649X interface connector to the host (microprocessor):

ADIS1649X       HOST MICROPROCESSOR
* DIO2 ———————> IRQ GPIO
* CS   <——————— SPI_SEL
* SCLK <——————— SPI_SCLK
* DIN  <——————— SPI_MOSI
* DOUT ———————> SPI_MISO

Note: IRQ GPIO can be connected to any DIOx pin. See the Devicetree section.

For a detailed description please see: Documentation/ABI/testing/sysfs-bus-iio

The sampling frequency of the device can be set by writing the desired value to the sampling_frequency file. The driver will automatically round up to the nearest supported sampling frequency.

Example:

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat sampling_frequency
4250.000000
pi@raspberrypi:/s
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> echo 2000 > sampling_frequency
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat sampling_frequency
2125.000000

A channel value can be read from its _raw attribute. The value returned by the _raw attribute is the raw value as reported by the device. To get the processed value of the channel in a standardized unit add the channels _offset attribute to the _raw value and multiply the result by _scale attribute. If no _offset attribute is present assume 0 for the offset.

processed value = (raw + offset) * scale

The units by the IIO framework are:

• Acceleration: Meter per Second squared
• Angular velocity: Rad per second
• Pressure: kilo Pascal
• Magnetometer: milli Gauss
• Temperature: milli Degree Celsius

Example:

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat in_accel_z_raw
265126938
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat in_accel_scale
0.002451731

Z-axis acceleration = in_accel_z_raw * in_accel_scale = 265126938 * 0.002451731 m/s^2 = 650019.932 m/s^2

The channels bandwidth can be set by writing the desired value to the channels _filter_low_pass_3db_frequency attribute. The driver will automatically round up to the nearest supported bandwidth.

Note that the low pass filter frequency depends on the sampling frequency, so changing the sampling frequency will scale the low pass filter frequency accordingly. E.g. reducing the sampling frequency by a factor of two will also reduce the bandwidth by a factor of two.

Example:

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat in_anglvel_filter_low_pass_3db_frequency
TDB
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> echo TBD > in_anglvel_filter_low_pass_3db_frequency
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat in_anglvel_filter_low_pass_3db_frequency
TBD

• ADIS1648x Evaluation on the EVAL-ADIS
• ADIS16375 Evaluation on the ADISUSB