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ADIS16220 IIO Programmable Digital Vibration Sensor Linux Driver

Supported Devices

Evaluation Boards

Description

This is a Linux industrial I/O (IIO) subsystem driver, targeting serial interface Accelerometer. 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.

Source Code

Status

Source Mainlined?
git Yes

Files

Declaring SPI slave devices

Unlike PCI or USB devices, SPI devices are not enumerated at the hardware level. Instead, the software must know which devices are connected on each SPI bus segment, and what slave selects these devices are using. For this reason, the kernel code must instantiate SPI devices explicitly. The most common method is to declare the SPI devices by bus number.

This method is appropriate when the SPI bus is a system bus, as in many embedded systems, wherein each SPI bus has a number which is known in advance. It is thus possible to pre-declare the SPI devices that inhabit this bus. This is done with an array of struct spi_board_info, which is registered by calling spi_register_board_info().

For more information see: Documentation/spi/spi-summary

21 Oct 2010 16:10 · Michael Hennerich

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_ADIS16220) \
	|| defined(CONFIG_ADIS16220_MODULE)
	{
		.modalias = "adis16220",
		.max_speed_hz = 1000000,     /* max spi clock (SCK) speed in HZ */
		.bus_num = 0,
		.chip_select = 5, /* 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);

Adding Linux driver support

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

The ADIS16220 Driver depends on CONFIG_SPI

Linux Kernel Configuration
	Device Drivers  --->
		[*] Staging drivers  --->
			<*>     Industrial I/O support --->
			    --- Industrial I/O support
			    -*-   Enable ring buffer support within IIO
			    -*-     Industrial I/O lock free software ring
			    -*-   Enable triggered sampling support

			          *** Accelerometers ***
			    [--snip--]

			    <*>   ADIS16220 Programmable Digital Vibration Sensor

			    [--snip--]

Hardware configuration

Driver testing

Each and every IIO device, typically a hardware chip, has a device folder under /sys/bus/iio/devices/iio:deviceX. Where X is the IIO index of the device. Under every of these directory folders reside a set of files, depending on the characteristics and features of the hardware device in question. These files are consistently generalized and documented in the IIO ABI documentation. In order to determine which IIO deviceX corresponds to which hardware device, the user can read the name file /sys/bus/iio/devices/iio:deviceX/name. In case the sequence in which the iio device drivers are loaded/registered is constant, the numbering is constant and may be known in advance.

02 Mar 2011 15:16 · Michael Hennerich

This specifies any shell prompt running on the target

root:/> cd /sys/bus/iio/devices/
root:/sys/bus/iio/devices> ls
iio:device0  trigger0


root:/sys/bus/iio/devices> cd iio:device0
root:/sys/devices/platform/bfin-spi.0/spi0.5/iio:device0> ls -l
-r--r--r--    1 root     root          2048 Jan  4 03:39 accel_bin
--w-------    1 root     root          4096 Jan  4 03:39 capture
-rw-r--r--    1 root     root          4096 Jan  4 03:39 capture_count
-r--r--r--    1 root     root          4096 Jan  4 03:39 dev
-r--r--r--    1 root     root          2048 Jan  4 03:39 in0_bin
-r--r--r--    1 root     root          2048 Jan  4 03:39 in1_bin
-rw-r--r--    1 root     root          4096 Jan  4 03:39 in_accel_offset
-rw-r--r--    1 root     root          4096 Jan  4 03:39 in_accel_peak_raw
-r--r--r--    1 root     root          4096 Jan  4 03:39 in_accel_raw
-rw-r--r--    1 root     root          4096 Jan  4 03:39 in_accel_scale
-rw-r--r--    1 root     root          4096 Jan  4 03:39 in_temp0_offset
-r--r--r--    1 root     root          4096 Jan  4 03:39 in_temp0_raw
-rw-r--r--    1 root     root          4096 Jan  4 03:39 in_temp0_scale
-r--r--r--    1 root     root          4096 Jan  4 03:39 in_voltage0_supply_raw
-rw-r--r--    1 root     root          4096 Jan  4 03:39 in_voltage0_supply_scale
-rw-r--r--    1 root     root          4096 Jan  4 03:39 in_voltage1_offset
-r--r--r--    1 root     root          4096 Jan  4 03:39 in_voltage1_raw
-rw-r--r--    1 root     root          4096 Jan  4 03:39 in_voltage1_scale
-r--r--r--    1 root     root          4096 Jan  4 03:39 in_voltage2_raw
-r--r--r--    1 root     root          4096 Jan  4 03:39 name
drwxr-xr-x    2 root     root             0 Jan  4 03:39 power
--w-------    1 root     root          4096 Jan  4 03:39 reset
lrwxrwxrwx    1 root     root             0 Jan  4 03:39 subsystem -> ../../../../../bus/iio
-rw-r--r--    1 root     root          4096 Jan  4 03:39 uevent

Show device name

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.5/iio:device0> cat name
adis16220

ADIS16220 device attributes

For a detailed description please see: drivers/staging/iio/Documentation/sysfs-bus-iio

Device files
accel_bin
capture
capture_count
dev
in0_bin
in1_bin
in_accel_offset
in_accel_peak_raw
in_accel_raw
in_accel_scale
in_temp0_offset
in_temp0_raw
in_temp0_scale
in_voltage0_supply_raw
in_voltage0_supply_scale
in_voltage1_offset
in_voltage1_raw
in_voltage1_scale
in_voltage2_raw
name
reset

Driver loading

This specifies any shell prompt running on the target

root:/> modprobe adis16220
adis16220: module is from the staging directory, the quality is unknown, you have been warned.
adis16220: at CS5 (irq 54)

Start a Capture

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.5/device0> echo 1 > capture

Read the current capture_count

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.5/device0> cat capture_count
0

Show single value from raw nodes

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.5/device0> cat in_accel_raw
1865
root:/sys/devices/platform/bfin-spi.0/spi0.5/device0>
root:/sys/devices/platform/bfin-spi.0/spi0.5/device0> cat in_accel_raw
1895

Read the entire capture buffer

You can also read the whole capture buffer by accessing the binary node in sysfs. For example, read accel_bin to get the capture buffer:

int main(int argc,char **argv)
{
        int fd, ret;
        unsigned short *val;
        char buffer[2048];
 
        if((fd=open("/sys/class/iio/device0/accel_bin",O_RDONLY))==-1) {
                printf("open /sys/class/iio/device0/accel_bin fail\n");
                exit(1);
        }
 
        ret = read(fd, buffer, 1024);
        if (ret < 0) {
                printf("read /sys/class/iio/device0/accel_bin fail\n");
                exit(1);
        } else {
                printf("read %d bytes from /sys/class/iio/device0/accel_bin\n", ret);
                int i;
 
                for (i = 0; i < ret; i += 2) {
                        val = buffer + i;
                        printf("%04x\n", *val);
                }
        }
 
        close(fd);
}

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