How the I2C Bus Works - EEWeb
How the I2C Bus Works - EEWeb
How the I2C Bus Works - EEWeb
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Supply<br />
SDA<br />
SCL<br />
Sub address<br />
decoder<br />
Quasi Output I 2 C I/O Expanders<br />
General Purpose I/O<br />
POR<br />
I 2 C-bus<br />
interface<br />
Latches<br />
Interrupt<br />
巨<br />
Input/ output stages<br />
alternative analog input<br />
configurations<br />
# of Outputs Interrupt<br />
KEY POINTS<br />
- Transfers keyboard, ACPI Power switch, keypad,<br />
switch or o<strong>the</strong>r inputs to microcontroller via I 2 C bus<br />
- Expand microcontroller via I 2 C bus where I/O can<br />
be located near <strong>the</strong> source or on various cards<br />
- Use outputs to drive LEDs, sensors, fans, enable<br />
and o<strong>the</strong>r input pins, relays and timers<br />
- Quasi outputs can be used as Input or Output<br />
without <strong>the</strong> use of a configuration register<br />
- The PCA9501 has 6 address pins, allowing up to 64<br />
devices to share <strong>the</strong> same I 2 C <strong>Bus</strong>.<br />
- Application Note, AN469 GPIO Selection, discusses<br />
pros and cons of GPIOs<br />
2Kbit<br />
EEPROM<br />
Interrupt and<br />
2Kbit EEPROM<br />
Quasi Output (20-25 ma sink and 100 uA source)<br />
8 PCF8574/74A PCA9500/58 PCA9501<br />
16 PCF8575/75C - -<br />
Semiconductors 35