{"id":2131,"date":"2024-07-15T13:08:57","date_gmt":"2024-07-15T13:08:57","guid":{"rendered":"https:\/\/iotthinghub.com\/?p=2131"},"modified":"2024-07-15T13:43:02","modified_gmt":"2024-07-15T13:43:02","slug":"i2c-fundamental","status":"publish","type":"post","link":"https:\/\/iotthinghub.com\/?p=2131","title":{"rendered":"I2C fundamental"},"content":{"rendered":"\n

I2<\/sup>C( read as I square C) bus first introduced by Philips. Because of its simplicity and flexibility the I2<\/sup>C bus has become one of the most microcontroller bus system used for interfacing various IC. The I2<\/sup>C bus use only 2 bidirectional data lines for communicating with the microcontroller and the I2<\/sup>C protocol specification can support up to 128(27-1) devices attached to the bus.
The I2<\/sup>C protocol use master and slave method, the master which is usually the microcontroller which the slave can be any I2<\/sup>C devices such as serial EEPROM, I\/O Expender or even another microcontroller. As the name I2<\/sup>C use only 2 pin to control up to 127 devices.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The 2 controlling pin are \u2013<\/p>\n\n\n\n

SDA: Serial Data pin.<\/p>\n\n\n\n

SCL: Serial Clock (Synchronize clock)<\/p>\n\n\n\n

Each slave devices have their own individual 7 bits of address length<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Bit0 represent R\/W, For Read bit0= 1 and Write bit0 = 0.<\/p>\n\n\n\n

Let\u2019s look at the bits available in AVR family-<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Let\u2019s make the user defined function of start, transmission and stop condition.<\/p>\n\n\n\n

uint8_t I2C_Start(void) -> TWI start or repeat start<\/p>\n\n\n

\nuint8_t I2C_Start(void)\n{\n\tTWCR=(1<<TWEN)|(1<<TWINT)|(1<<TWSTA); \/\/--- TWI Interrupt disable, TWI enable, TWI Start\n\twhile(!(TWCR&(1<<TWINT)));           \/\/--- Wait until start condition is executed\n\treturn(TWSR&0xF8);\n}\n<\/pre><\/div>\n\n\n
void I2C_Stop(void) -> TWI stop condition<\/p>\n\n\n
\nvoid I2C_Stop(void)\t\n{\n    TWCR=(1<<TWSTO)|(1<<TWINT)|(1<<TWEN);\/\/--- TWI Interrupt disable, TWI enable, TWI Stop\n    while(TWCR&(1<<TWSTO));\t              \/\/--- Wait until stop condition execution\n}\n<\/pre><\/div>\n\n\n
uint8_t I2C_Write(char data) -> TWI write condition<\/p>\n\n\n
\nuint8_t I2C_Write(char data)\n{\n\tTWDR=data;\n\tTWCR=(1<<TWEN)|(1<<TWINT);            \/\/--- TWI Interrupt disable, TWI enable\n\twhile(!(TWCR&(1<<TWINT)));            \/\/--- Wait until start condition is executed\n\treturn(TWSR&0xF8);\n}\n<\/pre><\/div>\n\n\n
Read function can be done with Acknowledge or without Acknowledge.<\/p>\n\n\n\n
char I2C_Read_Ack(void) -> Read with Acknowledge<\/p>\n\n\n
\nchar I2C_Read_Ack(void)\t\n{\n    TWCR=(1<<TWEN)|(1<<TWINT)|(1<<TWEA); \/\/--- TWI Interrupt disable, TWI enable, TWI Accknowledge\n    while(!(TWCR&(1<<TWINT)));           \/\/--- Wait until transmit is complete\n    return TWDR;\t\t\t             \/\/--- Return received data\n}\n<\/pre><\/div>\n\n\n
char I2C_Read_Nack(void) -> Read without Acknowledge<\/p>\n\n\n
\nchar I2C_Read_Nack(void)\t\t\n{\n    TWCR=(1<<TWEN)|(1<<TWINT);\t\/\/--- TWI Interrupt disable, TWI enable\n    while(!(TWCR&(1<<TWINT)));\t\/\/--- Wait until transmit is complete\n    return TWDR;\t\t        \/\/--- Return received data\n}\n<\/pre><\/div>\n\n\n
Those functions are used according to datasheet provided by the IC. We will Interface I2<\/sup>C in the next article.<\/p>\n","protected":false},"excerpt":{"rendered":"
I2C( read as I square C) bus first introduced by Philips. Because of its simplicity and flexibility the I2C bus has become one of the most microcontroller bus system used for interfacing various IC. The I2C bus use only 2 bidirectional data lines for communicating with the microcontroller and the I2C protocol specification can support […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19],"tags":[],"class_list":["post-2131","post","type-post","status-publish","format-standard","hentry","category-i2c"],"_links":{"self":[{"href":"https:\/\/iotthinghub.com\/index.php?rest_route=\/wp\/v2\/posts\/2131","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/iotthinghub.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/iotthinghub.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/iotthinghub.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/iotthinghub.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2131"}],"version-history":[{"count":13,"href":"https:\/\/iotthinghub.com\/index.php?rest_route=\/wp\/v2\/posts\/2131\/revisions"}],"predecessor-version":[{"id":2158,"href":"https:\/\/iotthinghub.com\/index.php?rest_route=\/wp\/v2\/posts\/2131\/revisions\/2158"}],"wp:attachment":[{"href":"https:\/\/iotthinghub.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2131"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/iotthinghub.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2131"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/iotthinghub.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2131"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}