I2C MUX Click is an quad bidirectional translating I2C and SMBus switch with reset function, intended for applications with I2C peripheral address conflicts (multiple, identical temp sensors). It features a quad bidirectional translating switch controlled via the I2C bus, labeled as TCA9546A from Texas Instruments. Click has three address jumpers, allowing up to eight TCA9546A devices on the same bus. I2C MUX Click allows voltage translation between 1.8V, 2.5V, 3.3V, and 5V buses, and also supports hot insertion. The TCA9546A can work on a 0 - 400 kHz clock frequency range and is ideal for communication with numerous devices that share the identical peripheral address on the same bus.
I2C MUX Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.
I2C MUX Click is packed with the TCA9546A, a quad bidirectional translating switch controlled via the I2C bus. The SCL/SDA upstream pair fans out to four downstream pairs, or channels. Any individual SCn/SDn channel or combination of channels can be selected, determined by the contents of the programmable control register. An active-low reset (RESET) input allows the TCA9546A to recover from a situation in which one of the downstream I2C buses is stuck in a low state. Pulling RESET low resets the I2C state machine and causes all the channels to be deselected, as does the internal power-on reset function. The pass gates of the switches are constructed such that the VCC pin can be used to limit the maximum high voltage, which will be passed by the TCA9546A. This allows the use of different bus voltages on each pair, so that 1.8-V, 2.5-V, or 3.3-V parts can communicate with 5-V parts without any additional protection. The peripheral devices can be connected to four headers located on the top of the I2C MUX Click.
The TCA9546A supports Standard-Mode (100 kHz) and Fast-Mode (400 kHz) operation. This way, the bus can be used to manage a single 8-bit control register in which the four least significant bits control the enabling and disabling of the 4 switch channels of I2C data flow. The I2C bus is for two-way two-line communication between different ICs or modules. The two lines are a serial data line (SDA) and a serial clock line (SCL). Both lines must be connected to a positive supply via a pullup resistor when connected to the output stages of a device. Data transfer can be initiated only when the bus is not busy. One data bit is transferred during each clock pulse. The data on the SDA line must remain stable during the high period of the clock pulse, as changes in the data line at this time are interpreted as control signals.
Applications of the TCA9546A contains an I2C (or SMBus) controller device and up to four I2C peripheral devices. The downstream channels are ideally used to resolve the I2C peripheral address conflicts. For example, if four identical digital temperature sensors are needed in the application, one sensor can be connected at each channel: 0, 1, 2, and 3. When the temperature at a specific location needs to be read, the appropriate channel can be enabled and all other channels switched off, the data can be retrieved, and the I2C controller can move on and read the next channel.
This Click board™ can be supplied and interfaced with both 3.3V and 5V without the need for any external components. The onboard SMD jumper labeled as VCC SEL allows voltage selection for interfacing with both 3.3V and 5V microcontrollers.
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