Circle6 data is transferred with the most significant

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circle6 Data is transferred with the Most Significant Bit (MSB) first. Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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I2C Bus – Byte Format circle6 9-th pulse: – transmitter releases SDA – receiver must hold SDA low in order to ack. received data – slave must release SDA after ack. bit (allows master to end frame)
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I2C Bus – Arbitration circle6 Arbitration refers to a portion of the protocol required only if more than one master will be used in the system. circle6 A master may start a transfer only if the bus is free. Two masters may generate a valid START condition on the bus. circle6 Arbitration is then required to determine which master will complete its transmission. Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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I2C Bus – Data Transfer circle6 After the START condition (S), a slave address is sent. circle6 This address is 7 bits long followed by an eighth bit which is a data direction bit (R/W) — a ‘zero’ indicates a transmission (WRITE), a ‘one’ indicates a request for data (READ). circle6 A data transfer is always terminated by a STOP condition (P) generated by the master. Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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I2C Bus – Possible Data Transfer Formats Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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Message protocols circle6 I²C defines three basic types of message, each of which begins with a START and ends with a STOP: circle6 Single message where a master writes data to a slave; circle6 Single message where a master reads data from a slave; circle6 Combined messages, where a master issues at least two reads and/or writes to one or more slaves.
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Message protocols circle6 In a combined message, each read or write begins with a START and the slave address. After the first START, these are also called repeated START bits; repeated START bits are not preceded by STOP bits, which is how slaves know the next transfer is part of the same message.
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I2C Bus – Other evolved variants circle6 SMBus – System Management Bus. circle6 PMBus – Power Management Bus. circle6 IPMI – Intelligent Platform Management Interface. Reference : UM10204 - I2C Bus Specification & User Manual from NXP Semiconductors
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SPI Bus – Introduction circle6 A Serial Peripheral Interface (SPI) system is a Master-Slave protocol. circle6 SPI consists of one master device and one or more slave devices. circle6 The master is defined as a microcontroller providing the SPI clock and the slave as any integrated circuit receiving the SPI clock from the master. circle6 SPI is also called “four wire” serial bus and operates in full- duplex mode. circle6 Standard has been defined by Motorola. Reference : TN15_SPI_Interface_Specification from VTI Technologies Reference : Getting started in SPI from Microchip
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SPI Bus – Features circle6 In SPI, data are always transferred in both directions.
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