S1	Idle state
S2	Init transfer in MASTER mode, send "I2C command" byte
S3	Send "transfer address" low byte
S4	Send "transfer address" high byte
S5	Send "byte count" byte
S6	Send block ("byte count" number of bytes, see S5)
S7	Receive block ("byte count" number of bytes, see S5)
S8	Finish transfer (set I2C stop condition)
S9	Init transfer in SLAVE mode, receive "I2C command" byte
S10	Receive "transfer address" low byte
S11	Receive "transfer address" high byte
S12	Receive "byte count" byte
S13	Receive block ("byte count" number of bytes, see S12)
S14	Send block ("byte count" number of bytes, see S12)
S15	Finish transfer (wait for I2C stop condition)