TSS463B datasheet(6/59 Pages) ATMEL

6 / 59 page

TSS463B

4102E–AUTO–12/04

Figure 3. SPI Data Stream

SCLK: Serial Clock

The master device provides the serial clock for the slave devices. Data is transferred

synchronously with this clock in both directions. The master and the slave devices

send/receive a data byte during an eight-clock pulse sequence.

MOSI: Master Out Slave In

The MOSI pin is the master device data output (CPU) and the slave device data input

(TSS463B). Data is transferred serially from the master to the slave on this line; most

significant bit (MSB) first, least significant bit (LSB) last.

MISO: Master In Slave Out

The MISO pin is configured as the slave device data output (TSS463B) and as master

device data input (CPU). When the slave device is not selected (SS = 1), this pin is in

high impedance state.

SS: Slave Select

The SS pin is the slave chip select. It is low active. A low state on the Slave Select input

allows the TSS463B to accept data on the MOSI pin and send data on the MISO pin.

The Slave Select signal must not toggle between each transmitted byte and should be

left at a low level during the whole SPI frame. SS must be asserted to inactive high level

at the end of the SPI frame.

As mentioned before, if SS is not asserted, MISO pin is in a high impedance state and

incoming data is not driven to the serial data register.

SPI Protocol

The general format of the data communication in the SPI frame between the TSS463B

and the host is a bit-for-bit exchange on each SCLK clock pulse. Data is arranged in the

TSS463B such that the significance of a bit is determined by its position from the start

for output and from the end for input, most significant bit (MSB) is sent first. Bit

exchanges in multiples of 8 bits are allowed.

The Idle Clock Polarity (CPOL) and the Clock Phase (CPHA) are not programmable: the

CPOL and CPHA values to be programmed in the master (CPU) are CPOL = CPHA = 1.

This is available for all modes. Waveforms with transmit and sample points are shown in

Figure 6.

0x55

SCLK

MOSI

SPI 8 Pulses

0x66

MISO

TSS463B bảng dữ liệu(PDF) 6 Page - ATMEL Corporation