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XR20V2172 Datasheet(PDF) 7 Page - Exar Corporation |
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XR20V2172 Datasheet(HTML) 7 Page - Exar Corporation |
7 / 53 page XR20V2172 7 REV. 1.0.1 TWO CHANNEL I2C/SPI UART WITH 64-BYTE FIFO AND RS232 TRANSCEIVER 2.0 FUNCTIONAL DESCRIPTIONS 2.1 CPU Interface The V2172 can operate with either an I2C-bus interface or an SPI interface. The CPU interface is selected via the I2C/SPI# input pin. 2.1.1 I2C-bus Interface The I2C-bus interface is compliant with the Standard-mode and Fast-mode I2C-bus specifications. The I2C- bus interface consists of two lines: serial data (SDA) and serial clock (SCL). In the Standard-mode, the serial clock and serial data can go up to 100 kbps and in the Fast-mode, the serial clock and serial data can go up to 400 kbps. The first byte sent by an I2C-bus master contains a start bit (SDA transition from HIGH to LOW when SCL is HIGH), 7-bit slave address and whether it is a read or write transaction. The next byte is the sub- address that contains the address of the register to access. The V2172 responds to each write with an acknowledge (SDA driven LOW by V2172 for one clock cycle when SCL is HIGH). If the TX FIFO is full, the V2172 will respond with a negative acknowledge (SDA driven HIGH by V2172 for one clock cycle when SCL is HIGH) when the CPU tries to write to the TX FIFO. The last byte sent by an I2C-bus master contains a stop bit (SDA transition from LOW to HIGH when SCL is HIGH). See Figures 3 - 5 below. For complete details, see the I2C-bus specifications. FIGURE 3. I2C START AND STOP CONDITIONS FIGURE 4. MASTER WRITES TO SLAVE (V2172) FIGURE 5. MASTER READS FROM SLAVE (V2172) SDA SCL S P START condition STOP condition SW A A AP SLAVE ADDRESS REGISTER ADDRESS nDATA White block: host to UART Grey block: UART to host SW A AR SLAVE ADDRESS REGISTER ADDRESS White block: host to UART Grey block: UART to host A S SLAVE ADDRESS nDATA ANA P LAST DATA |
Similar Part No. - XR20V2172_08 |
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Similar Description - XR20V2172_08 |
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