Quelltext der Seite Acceleration sensor (CM-i.MX27)

The DEV-i.MX27/35 contains a Three Axis Low-g Digital Output Accelerometer (MMA7455L).
A rudimentary device driver for Linux is available.

== Linux kernel configuration ==

 Device Drivers  --->
   <*> Hardware Monitoring support  --->
     <*>   MMA7450 device driver

== Linux test ==

* Boot Linux. You should see the following files in the kernel log:
 root@btmxc27:~# dmesg|grep mma7
 mma7450: i2c-bus: MXC I2C Adapter; address: 0x1d
 mma745x: before i2c_attach_client 0, adapter = c7cc2e00, address = 1d
 input: mma7450 as /class/input/input1
 mma7450 0-001d: mma7450 device is probed successfully.
 root@btmxc27:~# 

* You can view the chip's registers by reading the file ''/sys/class/hwmon/hwmon0/device/mma7450_ctl''

* Put the chip into measurement mode:
 echo "setmod 1" > /sys/class/hwmon/hwmon0/device/mma7450_ctl

* Then read the X, Y, and Z registers (0x0-0x5) periodically with this little script:
 #!/bin/sh
 while true
 do
 clear
 echo "readreg 1" > /sys/class/hwmon/hwmon0/device/mma7450_ctl
 echo "readreg 0" > /sys/class/hwmon/hwmon0/device/mma7450_ctl
 echo "readreg 3" > /sys/class/hwmon/hwmon0/device/mma7450_ctl
 echo "readreg 2" > /sys/class/hwmon/hwmon0/device/mma7450_ctl
 echo "readreg 5" > /sys/class/hwmon/hwmon0/device/mma7450_ctl
 echo "readreg 4" > /sys/class/hwmon/hwmon0/device/mma7450_ctl
 sleep 0.1
 done

* Take your DEV board and rotate it, you will see the corresponding numbers change.

[[Category:i.MX27]]