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SCI to SPI Peripheral Communication in V850ES Microcontrollers

When the CSI peripheral is not used, the SCK, SO, and SI I/O pins can be used as port pins. The CSI

units are configured using mode registers, control registers, configuration registers, and dedicated

hardware logic.

Table 1. Description of Registers

CSI Mode (8-bit) CSIM0n Specifies CSI operation

Control

Clock Selection CSICn Controls CSI serial transfer operation

Shift (8-, 16-bit) SIO0n/SIO0nL Converts parallel data to serial data

Receive Buffer (8-, 16-bit) SIRBn/SIRBnL Buffer register for receive data

Transmit Buffer (8-, 16-bit) SOTBn/SOTBnL Buffer register for transmit data

Configuration

Initial Transmit Buffer SOTBFn/SOTBFnL Stores initial data in continuous transfer mode

Clock Select Logic Selects the serial clock to be used

Serial Clock Counter Controls the serial clock to the Shift Register

Configuration

Hardware Logic

Interrupt Controller Controls interrupt request timing

The CSI Mode register configures the CSI unit for:

• Enabled or disabled operation

• Receive-only mode or transmit and receive mode

• 8- or 16-bit data length

• Most significant bit (MSB) or least significant bit (LSB) first

• Single or continuous transfer

Clock selection and CSI transfer operation depends on:

• Whether a positive or negative edge of the clock is used for the data capture strobe (clock polarity)

• Whether the first edge of clock is used for the ata capture or data drive strobe (clock phase)

For example, the timing diagram shown in Figure 2 illustrates a positive-edge data capture, with the first

edge of clock used for data capture and the trailing edge for data drive strobe. See type 4 in Figure 3.

It is important to note that the master unit controls the serial clock. If the first edge of the serial clock is

used for the data capture strobe, the slave unit must be ready with data (driving data) before the first edge

of the serial clock. Typically, in this case, the Chip Select signal is used to indicate the start of

transmission from the master unit.

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Directed Electronics 3200HS Technical Information Seite 9