Adding I²C write_i2c_block and read_i2c_block methods #1
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…py to properly link against the libi2c library
This adds mode 'i' for I2C_SMBUS_I2C_BLOCK_DATA. This is the same mode letter from i2cdump. Length is optional and defaults to 32 (maximum). The indended use is debugging i2c devices with shell commands.
…5-17) Specific warning: warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE Maybe both should have been defined: "To allow code that requires _BSD_SOURCE in glibc 2.19 and earlier and _DEFAULT_SOURCE in glibc 2.20 and later to compile without warnings, define both _BSD_SOURCE and _DEFAULT_SOURCE." Source: http://man7.org/linux/man-pages/man7/feature_test_macros.7.html at june 28th 2016.
By default current implementations of python smbus does not allow a i2c module to set i2c-address unless all kernel module references are removed. When such condition exists, python throws error like 'Device or resource busy'. But i2cget tool allows to open i2c address forcefully by a flag '-y'. This allows the shell script developers to read/write a i2c device at their own risk. But similar option is not in python smbus module (though it would be risky, if used unknowingly/inappropriately). This change allows such option in python code. Patch is 3 liner change. No interfaces were added . Developer just needs to set an environemnt variable named 'PY_SMBUS' with non-null string before calling SMBus(i2c-dev-bus-number). I have used this changed code to write a python program that queries the 9$ Chip computer's AXP209 I2C module for data collection wrt to battery
Usage of this python smbus module in 9$ Chip's axp209 module is in https://github.com/GssMahadevan/chip_axp209_tool
…ansaction in functions SMBus_write_i2c_block and SMBus_read_i2c_block.
…2c_master_recv functions.
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The write_i2c_block and read_i2c_block methods are required for some true I²C sensors like SHT31 or SDP610.