Differences
This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
|
en:netzer:i2c-master [2014/12/21 11:21] svesch Replaced TCP/IP with more generic socket |
en:netzer:i2c-master [2014/12/21 11:59] svesch Fixed image |
||
|---|---|---|---|
| Line 95: | Line 95: | ||
| The termination character stops any pending communication and also terminates any pending frame. | The termination character stops any pending communication and also terminates any pending frame. | ||
| + | |||
| + | |||
| + | |||
| + | |||
| + | ===== Examples ===== | ||
| + | |||
| + | The following examples presume that there is a [[connection|connection]] to Netzer. | ||
| + | |||
| + | Take a look at the following picture for circuiting a I2C EEPROM IC as slave to Netzer. | ||
| + | |||
| + | <imgcaption eeprom_example|Connecting a simple EEPROM to Netzer>{{:eeprom_example.png?direct}}</imgcaption> | ||
| + | |||
| + | |||
| + | |||
| + | ===== EEPROM slave address ===== | ||
| + | |||
| + | The EEPROM has the slave address 0x50. | ||
| + | Because the LSB is reserved for the R/W indicator the address is shifted left by one: //0xA0//. | ||
| + | |||
| + | |||
| + | ===== Writing to the EEPROM ===== | ||
| + | |||
| + | See the following byte sequence for writing a //0x55// to memory address 0 of the EEPROM: | ||
| + | <code> | ||
| + | Write per socket to Netzer: 0xA0 0x5C 0x00 0x55 0x00 | ||
| + | Answer from EEPROM received from Netzer: 0xFF 0xFF 0xFF 0x00 | ||
| + | </code> | ||
| + | |||
| + | - //0xA0// is the slave address with the R/W bit cleared, means write access. | ||
| + | - Netzer returns //0xFF//, indicating the available slave. | ||
| + | - //0x5C 0x00// transfers the memory address 0 - of course must be backslashed ('\\' = 0x5C) | ||
| + | - Netzer returns //0xFF//, successful transfered memory address. | ||
| + | - //0x55// is the value written to EEPROM | ||
| + | - Netzer returns //0xFF//, successful transfered value. | ||
| + | - //0x00// stops the transmission - I2C bus is released. | ||
| + | - Socket sends //0x00// to the host - Frame termination | ||
| + | |||
| + | |||
| + | ===== Reading from EEPROM ===== | ||
| + | |||
| + | <code> | ||
| + | Write per TCP/IP to Netzer: 0xA0 0x5C 0x00 0x73 0xA1 0xFF 0x00 | ||
| + | Answer from EEPROM received per TCP/IP from Netzer: 0xFF 0xFF 0xFF 0xFF 0x55 0x78 0x00 | ||
| + | </code> | ||
| + | |||
| + | - //0xA0// is the slave address with the R/W bit cleared, means write access. | ||
| + | - Netzer returns //0xFF//, indicating the available slave. | ||
| + | - //0x5C 0x00// transfers the memory address 0 - of course must be backslashed ('\\' = 0x5C) | ||
| + | - Netzer returns //0xFF//, successful transfered memory address. | ||
| + | - //0x73// initiates a repeated start on the bus. | ||
| + | - Netzer returns //0xFF//, successful repeated start. | ||
| + | - //0xA1// is the slave address with the R/W bit set, means read access. | ||
| + | - Netzer returns //0xFF//, indicating the available slave. | ||
| + | - //0xFF// from host: Pull me one byte from slave and acknowledge it. | ||
| + | - Netzer returns the value read from memory address 0: //0x55//. | ||
| + | - //0x00// from host: Pull me one more byte from slave and stop. | ||
| + | - Netzer returns the value read from memory address 1 (auto increment feature of the EEPROM): 0x78. | ||
| + | - Netzer automatically announces a stop condition after sending the byte. | ||
| + | - Socket sends //0x00// to the host - Frame termination | ||
