Circle6 it is a true multi master bus including

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circle6 It is a true multi-master bus including collision detection and arbitration to prevent data corruption if two or more masters simultaneously initiate data transfer. circle6 More than one IC capable of initiating a data transfer can be connected to it. The I2C protocol specification states that the IC that initiates a data transfer on the bus is considered the Bus Master. Consequently, at that time, all the other ICs are regarded to be Bus Slaves. Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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I2C Bus – Features circle6 Serial, 8-bit oriented, bidirectional data transfers can be made at Up to 100 kbit/s in the Standard-mode. Up to 400 kbit/s in the Fast-mode. Up to 1 Mbit/s in Fast-mode Plus. Up to 3.4 Mbit/s in the High-speed mode.
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Protocol circle6 Transfers are byte oriented, msb first circle6 Start: SDA goes low while SCL is high circle6 Master sends address of slave (7-bits) on next 7 clocks circle6 Master sends read/write request bit 0-write to slave 1-read from slave circle6 Slave ACKs by pulling SDA low on next clock circle6 Data transfers now commence
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I2C Bus – Terminology Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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I2C Bus – Signal Lines circle6 The two signal lines SDA and SCL are bidirectional lines, connected to a positive supply voltage via a pull-up resistor. circle6 When the bus is free, both lines are HIGH. The output stages of devices connected to the bus must have an open-drain or open- collector to perform the wired-AND function. Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors circle6 The levels of the logical ‘0’ (LOW) and ‘1’ (HIGH) are set as 30% and 70% of VDD; VIL is 0.3VDD and VIH is 0.7VDD.
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I2C Bus – Data Validity circle6 The data on the SDA line must be stable during the HIGH period of the clock. circle6 The HIGH or LOW state of the data line can only change when the clock signal on the SCL line is LOW. circle6 One clock pulse is generated for each data bit transferred. Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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I2C Bus – START & STOP Condition circle6 All transactions begin with a START (S) and can be terminated by a STOP (P). circle6 A HIGH to LOW transition on the SDA line while SCL is HIGH defines a START condition. circle6 A LOW to HIGH transition on the SDA line while SCL is HIGH defines a STOP condition. circle6 START and STOP conditions are always generated by the master. Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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I2C Bus – Byte Format circle6 Every byte put on the SDA line must be 8 bits long. circle6 The number of bytes that can be transmitted per transfer is unrestricted. circle6 Each byte has to be followed by an Acknowledge bit.
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