Directed Electronics 3200HS Informações Técnicas descarregar pdf (Página 20)

CSI to SPI Peripheral Communication in V850ES Microcontrollers

The V850ES MCU’s CSI peripheral is used for communication with the temperature sensor devices,

which have built-in SPI peripheral interfaces. For remote sensing of temperature, the MAX6627

temperature sensor uses a diode-connected NPN-type transistor that connects to the temperature-sensing

device through a twisted cable and senses the local temperature of the device.

Figure 10. MAX6627 Diode-Connected NPN-Type Transistor

NEC

V850ES-Series

Microcontroller

LED-1 LED-2

SW2 SW3

8-Bit

Output Port

8-Bit

Output Port

Input Port Pin

SDI

SCLK

Port-Pin

SCK

DS1722

Port-Pin

Diode-Connected

NPN-Type Transistor

DxP

DxN

/CS

SDO

SCK

MAX6627

SDO

SERMODE

VCC

LED-1 and LED-2

When interfacing with an SPI peripheral, it is necessary to configure the interface from the NEC

Electronics V850ES MCU using the clocked serial interface.

1. Determine the SPI peripheral clocking method used.

2. Configure the V850ES MCU’s CSI for the equivalent SPI clocking method.

3. Set appropriate registers for the selected CSI unit.

For the MAX6627, the SPI clocking method required is CPOL=0 (SCK idle state low), CPHA=0 (data

capture strobe on first clock edge). This requires an NEC Electronics CSI type 4 interface (CKPn=1,

DAPn=1).

For the DS1722, the SPI clocking method can have either CPOL=0 (SCK idle state low) if SCK is low

when CE is asserted, or CPOL=1 if SCK is high when CE is asserted. In either case, the clock phase

required is CPHA=1 (data driven on first clock edge, data capture strobe on clock trailing edge). If we

assume CPOL=0, this would require an NEC Electronics CSI type 3 interface.

Since NEC Electronics MCUs often have multiple CSI peripherals, it would be possible to connect the

MAX6627 to one set of CSI pins and the DS1722 to another set. However, since the NEC Electronics

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