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README.md

cI2C

Arduino Hardware I2C for AVR (plain c)

Hardware I2C library for AVR MCUs (lib intended for I2C protocols development in c, for easier ports to other MCUs)

Library choice:

  • cI2C library implements I2C bus for AVR tagets (Uno, Nano, Mega...)
    • you may prefer this one when:
      • working on AVR targets
      • interrupts are not needed
  • WireWrapper implements I2C bus for every platform that includes Wire library
    • you would have to use this one when:
      • working on non-AVR targets
      • portability is needed (using Wire library)

No refactoring is required when switching between cI2C & WireWrapper libs; Both libs share same Typedefs, Functions & Parameters.

Notes:

  • cI2C is written in plain c (intentionally)
  • cI2C does not use any interrupt (yet, but soon will have to)
  • cI2C is designed to act as bus Master (Slave mode will be considered in future releases)
  • cI2C is set to work on AVR targets only
    • for other targets, you may use WireWrapper instead (will be using Wire)

Usage:

This library is intended to be able to work with multiple slaves connected on the same I2C bus. Thus, the I2C bus and Slaves are defined separately.

  • On one hand, I2C bus has to be initialised with appropriate speed:
    • use I2C_init(speed): speed can be choosen from I2C_SPEED enum for convenience, or passing an integer as parameter
  • On the other hand, Slave(s) have to be defined and initialised too:
    • use I2C_SLAVE typedef to declare slaves structs
    • use I2C_slave_init(pSlave, addr, regsize)
      • pSlave is a pointer to the slave struct to initialise
      • addr is the slave I2C address (don't shift addr, lib takes care of that)
      • regsize is the width of internal slave registers (to be choosen from I2C_INT_SIZE)
    • in case you need to use custom R/W procedures for a particular slave:
      • use I2C_slave_set_rw_func(pSlave, pFunc, rw)
        • pSlave is a pointer to the slave declaration to initialise
        • pFunc is a pointer to the Read or Write bypass function
        • rw can be choosen from I2C_RW enum (wr=0, rd=1)

After all inits are done, the lib can basically be used this way:

  • I2C_read(pSlave, regaddr, pData, bytes)
    • pSlave is a pointer to the slave struct to read from
    • regaddr is the start address to read from
    • pData is a pointer to the place where datas read will be stored
    • bytes number of bytes to read from slave
    • returns true if read is ok, false otherwise
  • I2C_write(pSlave, regaddr, pData, bytes)
    • pSlave is a pointer to the slave struct to write to
    • regaddr is the start address to write to
    • pData is a pointer to the block of datas to write to slave
    • bytes number of bytes to write to slave
    • returns true if write is ok, false otherwise

Examples included:

following examples should work with any I2C EEPROM/FRAM with address 0x50 (yet function to get Chip ID are device dependant (and will probably only work on FUJITSU devices))

  • ci2c_master_write.ino: Write some bytes to FRAM and compare them with what's read afterwards
  • ci2c_master_read.ino: Read some bytes in FRAM
  • ci2c_advanced.ino: Redirecting slave write & read functions (to custom functions following typedef)

Doxygen doc can be generated for the library using doxyfile

Feel free to share your thoughts @ xgarmanboziax@gmail.com about:

  • issues encountered
  • optimisations
  • improvements & new functionalities

cI2C

WireWrapper