Using the Aardvark adapter with a Microwire device

What is Microwire?

Microwire is a serial communication interface which is a subset of the SPI serial communication bus. SPI has four different modes of operation which are based on two parameters: the Clock Phase (CPHA) and Clock Polarity (CPOL). For more information about the SPI modes, please refer to SPI Background.

Microwire has a single mode, CPHA=0 (the leading edge is rising and the trailing edge is falling) and CPOL=0 (the sample is on the leading edge and the setup is on the trailing edge).

How to interface a Microwire device

Essentially, the Aardvark I2C/SPI Host Adapter would interface with a Microwire device in the same manner as a regular SPI device. The only difference is the label of the pins.

The Microwire pins are: serial clock (SK), serial in (SI), serial out (SO) and chip select (CS#).

If the Aardvark I2C/SPI Host Adapter is used as a master device to interface with a slave Microwire device, the pins would be connected in the following manner.

SPI Master	Microwire Slave
SCLK	SK
MOSI	SI
MISO	SO
SS#	CS#

If the Aardvark I2C/SPI Host Adapter is used as a slave device to interface with a master Microwire device, the pins would be connected in the following manner.

SPI Slave	Microwire Master
SCLK	SK
MOSI	SO
MISO	SI
SS#	CS#

References

• Microwire Serial Interface Application Notes - National Semiconductors
• Serial buses information page - Microwire