Class: I2C::LinuxI2Cdev

Inherits:
Object
  • Object
show all
Defined in:
lib/mruby/i2c.rb

Overview

I2C bus driver

only implement high-level methods.

Constant Summary collapse

I2C_SLAVE =

see /usr/include/linux/i2c.h i2c-dev.h

0x0703
I2C_RDWR = 
0x0707
I2C_M_RD = 
0x0001

Instance Method Summary collapse

Constructor Details

#initialize(node, *params) ⇒ LinuxI2Cdev

constructor

Parameters:

  • node (String) —

    device node of I2C

  • params (nil) —

    dummy.

See Also:



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# File 'lib/mruby/i2c.rb', line 49

def initialize(node, *params)
  @device = File.open(node, "r+:ASCII-8BIT")
end

Instance Method Details

#read_ioctl(i2c_adrs_7, read_bytes, *param) ⇒ String Also known as: read

Reads data of read_bytes bytes from the device with the address i2c_adrs_7. using ioctl

Parameters:

  • i2c_adrs_7 (Integer) —

    I2C slave address (7bit address)

  • read_bytes (Integer) —

    read bytes.

  • param (Integer, String, Array<Integer>) —

    output data before reading.

Returns:

  • (String) —

    reading datas.



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# File 'lib/mruby/i2c.rb', line 82

def read_ioctl( i2c_adrs_7, read_bytes, *param )
  out_data = _rebuild_output_data( param )
  recv_data = "\x00".b * read_bytes

  # prepare the struct i2c_msg[2]
  # struct i2c_msg {
  #        __u16 addr;
  #        __u16 flags;
  #        __u16 len;         << hidden padding _u16
  #        __u8 *buf;
  # };
  i2c_msg_s = [ i2c_adrs_7, 0, out_data.bytesize, 0,
                [out_data].pack('p').unpack1('J') ].pack('SSSSJ')
  i2c_msg_r = [ i2c_adrs_7, I2C_M_RD, read_bytes, 0,
                [recv_data].pack('p').unpack1('J') ].pack('SSSSJ')

  # prepare the struct i2c_rdwr_ioctl_data
  # struct i2c_rdwr_ioctl_data {
  #         struct i2c_msg *msgs;   /* pointers to i2c_msgs */
  #         __u32 nmsgs;            /* number of i2c_msgs */
  # };
  if out_data.empty?
    arg = [ [i2c_msg_r            ].pack('P').unpack1('J'), 1 ].pack('JL')
  else
    arg = [ [i2c_msg_s + i2c_msg_r].pack('P').unpack1('J'), 2 ].pack('JL')
  end

  @device.ioctl( I2C_RDWR, arg )
  return recv_data
end

#read_sysread(i2c_adrs_7, read_bytes, *param) ⇒ Object

Reads data of read_bytes bytes from the device with the address i2c_adrs_7. using sysread

See Also:



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# File 'lib/mruby/i2c.rb', line 64

def read_sysread( i2c_adrs_7, read_bytes, *param )
  out_data = _rebuild_output_data( param )

  _use_slave_adrs( i2c_adrs_7 )
  @device.syswrite( out_data )  if !out_data.empty?
  @device.sysread( read_bytes )
end

#write(i2c_adrs_7, *outputs) ⇒ Integer

Writes data specified in outputs to the device with the address i2c_adrs_7.

Parameters:

  • i2c_adrs_7 (Integer) —

    I2C slave address (7bit address)

  • outputs (Integer, String, Array<Integer>) —

    output data.

Returns:

  • (Integer) —

    number of bytes actually write.



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# File 'lib/mruby/i2c.rb', line 123

def write( i2c_adrs_7 , *outputs )
  out_data = _rebuild_output_data( outputs )

  _use_slave_adrs( i2c_adrs_7 )
  @device.syswrite( out_data )
end