Bus Communication

Why Use Open-Drain Output and Pull-Up Resistors in I2C?

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Why Use Open-Drain Output and Pull-Up Resistors in I2C?

Why do we need pull-up resistors in I2C? Because it uses open-drain output. Why is it open-drain output? The I2C protocol supports multiple master devices and multiple slave devices on a single bus. If push-pull output is used instead of open-drain output, it could lead to short circuits between master devices. Therefore, the bus generally … Read more

Why Is the CAN Bus Termination Resistor 120Ω?

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Why Is the CAN Bus Termination Resistor 120Ω?

The termination resistor for the CAN bus is generally 120 ohms. In fact, during design, it consists of two 60 ohm resistors connected in series. There are typically two nodes of 120Ω on the bus, which is a well-known fact for anyone with a basic understanding of the CAN bus. However, as someone who struggles … Read more