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 Adapteris 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