Jpf5Ap1rR6E/hqdefault.jpg' alt='C Source Code Serial Port Communication Visual Basic' title='C Source Code Serial Port Communication Visual Basic' />IC Wikipedia. Not to be confused with IS. IC Inter Integrated Circuit, pronounced I squared C, is a multi master, multi slave, packet switched, single ended, serialcomputer bus invented by Philips Semiconductor now NXP Semiconductors. It is typically used for attaching lower speed peripheral ICs to processors and microcontrollers in short distance, intra board communication. MSDN Magazine Issues and Downloads. Read the magazine online, download a formatted digital version of each issue, or grab sample code and apps. Alternatively IC is spelled I2. C pronounced I two C or IIC pronounced I I C. Since October 1. 0, 2. IC protocol. However, fees are required to obtain IC slave addresses allocated by NXP. Several competitors, such as Siemens AG later Infineon Technologies AG, now Intel mobile communications, NEC, Texas Instruments, STMicroelectronics formerly SGS Thomson, Motorola later Freescale, now merged with NXP2, Nordic Semiconductor and Intersil, have introduced compatible IC products to the market since the mid 1. SMBus, defined by Intel in 1. IC, defining a stricter usage. One purpose of SMBus is to promote robustness and interoperability. Accordingly, modern IC systems incorporate some policies and rules from SMBus, sometimes supporting both IC and SMBus, requiring only minimal reconfiguration either by commanding or output pin use. SAM_1373.JPG' alt='C Source Code Serial Port Communication Visual Basic' title='C Source Code Serial Port Communication Visual Basic' />RevisionseditThe history of IC specification releases In 1. Hz IC system was created as a simple internal bus system for building control electronics with various Philips chips. Exhibition The place to share and show off projects Until someone finds a way to categorize what is here, be sure to remember that your browser has a find in. In 1. 99. 2, Version 1 added 4. Hz Fast mode Fm and a 1. This was the first standardized version. In 1. 99. 8, Version 2 added 3. MHz High speed mode Hs with power saving requirements for electric voltage and current. In 2. 00. 0, Version 2. In 2. 00. 7, Version 3 added 1 MHz Fast mode plus Fm using 2. A drivers, and a device ID mechanism. In 2. 01. 2, Version 4 added 5 MHz Ultra Fast mode UFm for new USDA data and USCL clock lines using push pull logic without pull up resistors, and added an assigned manufacturer ID table. It is only a unidirectional bus. In 2. 01. 2, Version 5 corrected mistakes. In 2. 01. 4, Version 6 corrected two graphs. This is the most recent standard. IC uses only two bidirectional open drain lines, Serial Data Line SDA and Serial Clock Line SCL, pulled up with resistors. Typical voltages used are 5 V or 3. V, although systems with other voltages are permitted. The IC reference design has a 7 bit or a 1. Common IC bus speeds are the 1. Recent revisions of IC can host more nodes and run at faster speeds 4. Fast mode, 1 Mbits Fast mode plus or Fm, and 3. Mbits. High Speed mode. These speeds are more widely used on embedded systems than on PCs. Denver Developmental Screening Test Training Manual more. There are also other features, such as 1. Note the bit rates are quoted for the transactions between master and slave without clock stretching or other hardware overhead. Protocol overheads include a slave address and perhaps a register address within the slave device, as well as per byte ACKNACK bits. Thus the actual transfer rate of user data is lower than those peak bit rates alone would imply. For example, if each interaction with a slave inefficiently allows only 1 byte of data to be transferred, the data rate will be less than half the peak bit rate. The maximal number of nodes is limited by the address space and also by the total bus capacitance of 4. F, which restricts practical communication distances to a few meters. The relatively high impedance and low noise immunity requires a common ground potential, which again restricts practical use to communication within the same PC board or small system of boards. Reference designeditThe aforementioned reference design is a bus with a clock SCL and data SDA lines with 7 bit addressing. The bus has two roles for nodes master and slave Master node node that generates the clock and initiates communication with slaves. Slave node node that receives the clock and responds when addressed by the master. The bus is a multi master bus, which means that any number of master nodes can be present. Additionally, master and slave roles may be changed between messages after a STOP is sent. There may be four potential modes of operation for a given bus device, although most devices only use a single role and its two modes master transmit master node is sending data to a slave,master receive master node is receiving data from a slave,slave transmit slave node is sending data to the master,slave receive slave node is receiving data from the master. The master is initially in master transmit mode by sending a start bit followed by the 7 bit address of the slave it wishes to communicate with, which is finally followed by a single bit representing whether it wishes to write 0 to or read 1 from the slave. If the slave exists on the bus then it will respond with an ACK bit active low for acknowledged for that address. The master then continues in either transmit or receive mode according to the readwrite bit it sent, and the slave continues in its complementary mode receive or transmit, respectively. The address and the data bytes are sent most significant bit first. The start bit is indicated by a high to low transition of SDA with SCL high the stop bit is indicated by a low to high transition of SDA with SCL high. All other transitions of SDA take place with SCL low. If the master wishes to write to the slave, then it repeatedly sends a byte with the slave sending an ACK bit. In this situation, the master is in master transmit mode, and the slave is in slave receive mode. If the master wishes to read from the slave, then it repeatedly receives a byte from the slave, the master sending an ACK bit after every byte except the last one. In this situation, the master is in master receive mode, and the slave is in slave transmit mode. The master then either ends transmission with a stop bit, or it may send another START bit if it wishes to retain control of the bus for another transfer a combined message. Message protocolseditIC defines basic types of messages, each of which begins with a START and ends with a STOP Single message where a master writes data to a slave. Single message where a master reads data from a slave. Combined messages, where a master issues at least two reads or writes to one or more slaves. In a combined message, each read or write begins with a START and the slave address. After the first START in a combined message these are also called repeated START bits. Repeated START bits are not preceded by STOP bits, which is how slaves know that the next transfer is part of the same message. Any given slave will only respond to certain messages, as specified in its product documentation. Pure IC systems support arbitrary message structures. SMBus is restricted to nine of those structures, such as read word N and write word N, involving a single slave. PMBus extends SMBus with a Group protocol, allowing multiple such SMBus transactions to be sent in one combined message. The terminating STOP indicates when those grouped actions should take effect. For example, one PMBus operation might reconfigure three power supplies using three different IC slave addresses, and their new configurations would take effect at the same time when they receive that STOP. With only a few exceptions, neither IC nor SMBus define message semantics, such as the meaning of data bytes in messages. Message semantics are otherwise product specific. Those exceptions include messages addressed to the IC general call address 0x.