Difference between revisions of "Example SPI test"
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This is a guide to the <code>spi_test</code> example project included in the EMAC OE SDK. | This is a guide to the <code>spi_test</code> 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. | + | <code>SPI</code> (Serial Peripheral Interface) is a synchronous full duplex serial data communication standard used to interface many types of memory and I/O devices. <code>SPI</code> requires four lines per slave device connection, three of which are shared across the <code>SPI</code> 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 <code>spi_test</code> C example project. This is an example test interface for sending a transaction to an EMAC <code>SPI</code> device interface. It is only relevant if the EMAC <code>SPI</code> device interface is enabled for an external <code>SPI</code> 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. | This procedure provides an overview of how to compile and run the <code>spi_test</code> C example project. This is an example test interface for sending a transaction to an EMAC <code>SPI</code> device interface. It is only relevant if the EMAC <code>SPI</code> device interface is enabled for an external <code>SPI</code> 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 | + | For more information about the <code>SPI</code> protocol see the following page: http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus |
The <code>spi_test</code> project builds one executable: <code>spi_test</code>. | The <code>spi_test</code> project builds one executable: <code>spi_test</code>. | ||
| Line 31: | Line 31: | ||
:* length: Length of <code>spi</code> transactions in bytes. | :* length: Length of <code>spi</code> transactions in bytes. | ||
:* mosi: Hex value to be transmitted in hexadecimal. | :* mosi: Hex value to be transmitted in hexadecimal. | ||
| + | |||
| + | root@emac-oe~:$ ./spi_test /dev/mcp3208 4 12ABCDEF | ||
| + | |||
| + | This command was run on an EMAC SoM-150ES carrier board. The results will appear in the terminal: | ||
| + | <syntaxhighlight lang=console> | ||
| + | MOSI MISO | ||
| + | 12 : 00 | ||
| + | AB : 00 | ||
| + | CD : 00 | ||
| + | EF : 00 | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | |||
| + | == Summary == | ||
| + | The <code>spi_test</code> C example project demonstrates how to use the <code>SPI</code> device. <code>SPI</code> 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. | ||
Revision as of 16:29, 21 February 2014
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
The spi_test project builds one executable: spi_test.
Contents
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.
Alternatively, the 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
Hardware Requirements
The spi_test C example project will run on any EMAC carrier board which has an SPI interface (see also the EMAC SPI Programming page).
Using spi_test
The spi_test program is executed from the console. It takes three parameters.
root@emac-oe~:$ ./spi_test device length mosi
- device: Name of the
spidevice node. - length: Length of
spitransactions in bytes. - mosi: Hex value to be transmitted in hexadecimal.
- device: Name of the
root@emac-oe~:$ ./spi_test /dev/mcp3208 4 12ABCDEF
This command was run on an EMAC SoM-150ES carrier board. The results will appear in the terminal:
MOSI MISO
12 : 00
AB : 00
CD : 00
EF : 00
Summary
The spi_test C example project demonstrates how to use the SPI device. 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.
