Technical information

CSI to SPI Peripheral Communication in V850ES Microcontrollers
Figure 6.
Data-In
Data-Out
Chip Select
CPHA = 0
DAPn = 1
Chip Select
CPHA = 1
DAPn = 0
Byte - 1 Byte - 2
2.4 Examples of SPI Peripherals
The following examples of SPI peripherals show two temperature sensors, with similar but slightly
different SPI hardware. This application note will show how both of these devices can be interfaced to an
NEC Electronics MCU without additional hardware.
2.4.1 Maxim MAX6627
The Maxim MAX6627 is a remote temperature sensor with a built-in SPI-compatible serial
interface that connects to a remote diode-connected transistor for sensing temperature of the
transistor.
The MAX6627 sensor is a read-only slave device that has SCK (serial clock) and SDO (serial data
output) pins, but no serial data input pin. The SCK input is driven by the master unit; the SDO
output would be connected to the SI (serial input) of the master.
The CS (chip select) pin controls sensing and communication. When CS is high, the MAX6627
performs a temperature conversion once every second and stores the result internally. When CS is
low, the MAX6627 stops conversion, and is selected for communication. This means CS must be
driven by the master.
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