Example SPI test
This is a guide to the
spi_test example project included in the EMAC OE SDK.
SPI (Serial Peripheral Interface) is a synchronous full duplex serial data communication standard used to interface many types of memory and I/O devices.
SPI requires four lines per slave device connection, three of which are shared across the
SPI bus. MISO, MOSI and SCLK are the three shared bus lines and chip selects (CSn) are used to determine which device is the target for communication.
This procedure provides an overview of how to compile and run the
spi_test C example project. This is an example test interface for sending a transaction to an EMAC
SPI device interface. It is only relevant if the EMAC
SPI device interface is enabled for an external
SPI device that is connected to the bus. It assumes familiarity with the C programming language and is intended to be used by experienced programmers who are looking to learn the EMAC SDK.
For more information about the
SPI protocol see the following page: http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus
spi_test project builds one executable:
Opening, Building, and Uploading the Project Files
For information on opening the project from within Eclipse, please see, Importing the EMAC OE SDK Projects with Eclipse. Then, follow Using the EMAC OE SDK Projects with Eclipse for information on how to build, upload, and execute the example.
Makefile can be used with the
make command from the command-line to build and upload the example. For more information on this method, please see, Using EMAC OE SDK Example Projects.
Usage and Behavior
spi_test C example project will run on any EMAC carrier board which has an
SPI interface (see also the EMAC SPI Programming page).
spi_test program is executed from the console. It takes three parameters.
root@emac-oe~:$ ./spi_test device length mosi
- device: Name of the
- length: Length of
spitransactions in bytes.
- mosi: Hex value to be transmitted in hexadecimal.
- device: Name of the
This example command was run on an EMAC SoM-150ES carrier board. Test results will be displayed in the terminal.
root@emac-oe~:$ ./spi_test /dev/mcp3208 1 12 MOSI MISO 12 : 00
After running the ./spi_test /devmcp3208 1 12 command, the program displays MOSI in hexadecimal and then outputs MISO.
spi_test C example project demonstrates how to use the
SPI enables the serial exchange of data between two devices, one called a master and the other called a slave. It operates in full duplex mode.