I2C MUX 6 Click is a compact add-on board representing a bidirectional selector dedicated to I2C peripheral address conflicts applications. This board features the PCA9518, an expandable five-channel bidirectional buffer controlled by the I2C-bus from Texas Instruments. The PCA9518 overcomes the restriction of maximum bus capacitance by separating and buffering the I2C data (SDA) and clock (SCL) lines into multiple groups of 400pF I2C channels. It provides activation of the desired channel via a given Enable pin and permits extension of the I2C-bus, through an onboard expansion header, by buffering both the data (SDA) and the clock (SCL) lines enabling virtually an unlimited number of buses of 400pF. This Click board™ is suitable for various applications from industrial to medical, communications, and automotive systems.
I2C MUX 6 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.
I2C MUX 6 Click as its foundation uses the PCA9518, an expandable four-channel bidirectional buffer controllable through the I2C serial interface from Texas Instruments. The primary SCL/SDA signal pair is directed to four channels where only one SCL/SDA channel can be selected at a time, determined on the state of the four Enable pins, routed to the AN, RST, CS, and PWM pins of the mikroBUS™ socket. The PCA9518 overcomes the restriction of maximum bus capacitance by separating and buffering the I2C data (SDA) and clock (SCL) lines into multiple groups of 400pF I2C channels.
The PCA9518 has several multi-directional open-drain buffers designed to support the standard low-level-contention arbitration of the I2C bus. Except during arbitration, the PCA9518 acts like a pair of non-inverting open-drain buffers, one for SDA and one for SCL. It can communicate with other PCA9518 hubs through a 4-wire inter-hub expansion bus, located on the onboard header with EXP labeled pins, i.e., permits extension of the I2C-bus by buffering both the data (SDA) and the clock (SCL) lines enabling virtually an unlimited number of buses of 400pF.
The PCA9518 communicates with MCU using the standard I2C interface that supports Standard-Mode (100 kHz) and Fast-Mode (400 kHz) operation. As mentioned before, each Enable pin, ENx, controls its associated SDAx and SCLx channels. When the ENx pin is in a low logic state, it isolates its corresponding SDAx and SCLx lines from the system by blocking the inputs from SDAx and SCLx and disabling the output drivers on these lines. It is essential that the ENx change state only when both the global bus and the local port are in an IDLE state to prevent system failures.
This Click board™ is designed for 3.3V operation. It also has onboard terminals labeled as VCC-I2C to supply a voltage, 3.3V or 5V, for PCA9518’s I2C lines, which are 5V-tolerant. However, the board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. The Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.
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