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Doc: Fix broken SPI Tool documentation

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This commit is contained in:
Alan C. Assis
2024-08-14 12:16:31 -07:00
committed by Xiang Xiao
parent f05c85e622
commit a409c42d13
1 changed files with 14 additions and 12 deletions
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Documentation/applications/system/spi/index.rst
+14 -12
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@@ -2,7 +2,7 @@
``spi`` SPI Tool ``spi`` SPI Tool
================ ================
The I2C tool provides a way to debug SPI related problems. This README file will The SPI Tool provides a way to debug SPI related problems. This README file will
provide usage information for the SPI tools. provide usage information for the SPI tools.
Contents Contents
@@ -29,10 +29,10 @@ Contents
* ``set`` * ``set``
* ``verf`` * ``verf``
- I2C Build Configuration - SPI Build Configuration
* NuttX Configuration Requirements * NuttX Configuration Requirements
* I2C Tool Configuration Options * SPI Tool Configuration Options
System Requirements System Requirements
------------------- -------------------
@@ -71,7 +71,7 @@ or::
nsh> spi ? nsh> spi ?
Here is an example of the help output. I shows the general form of the command Here is an example of the help output. It shows the general form of the command
line, the various SPI commands supported with their unique command line options, line, the various SPI commands supported with their unique command line options,
and a more detailed summary of the command SPI command options:: and a more detailed summary of the command SPI command options::
@@ -95,8 +95,8 @@ and a more detailed summary of the command SPI command options::
**Notes**: **Notes**:
- An environment variable like $PATH may be used for any argument. - An environment variable like $PATH may be used for any argument.
- Arguments are _sticky_. For example, once the SPI address is specified, that - Arguments are _sticky_. For example, once the SPI bus is specified, that
address will be re-used until it is changed. bus will be re-used until it is changed.
**Warning**: **Warning**:
@@ -117,7 +117,7 @@ SPI operation. Those arguments vary from command to command as described below.
However, there is also a core set of common ``OPTIONS`` supported by all commands. However, there is also a core set of common ``OPTIONS`` supported by all commands.
So perhaps a better representation of the general SPI command would be:: So perhaps a better representation of the general SPI command would be::
i2c <cmd> [OPTIONS] [arguments] spi <cmd> [OPTIONS] [arguments]
Where ``[OPTIONS]`` represents the common options and and arguments represent the Where ``[OPTIONS]`` represents the common options and and arguments represent the
operation-specific arguments. operation-specific arguments.
@@ -146,7 +146,7 @@ Environment Variables
variables. Environment variables must be preceded with the special character variables. Environment variables must be preceded with the special character
``$``. For example, ``PWD`` is the variable that holds the current working directory ``$``. For example, ``PWD`` is the variable that holds the current working directory
and so ``$PWD`` could be used as a command line argument. The use of environment and so ``$PWD`` could be used as a command line argument. The use of environment
variables on the I2C tools command is really only useful if you wish to write variables on the SPI tools command is really only useful if you wish to write
NSH scripts to execute a longer, more complex series of SPI commands. NSH scripts to execute a longer, more complex series of SPI commands.
Common Option Summary Common Option Summary
@@ -187,7 +187,7 @@ Common Option Summary
Various SPI devices support different data widths. This option is untested. Various SPI devices support different data widths. This option is untested.
- ``[-f freq]`` I2C frequency. Default: ``4000000`` Current: ``4000000`` - ``[-f freq]`` SPI frequency. Default: ``4000000`` Current: ``4000000``
The ``[-f freq]`` sets the frequency of the SPI device. The default is very The ``[-f freq]`` sets the frequency of the SPI device. The default is very
conservative. conservative.
@@ -212,7 +212,9 @@ Exchange data: ``exch [OPTIONS] <Optional TX Data>``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This command triggers an SPI transfer, returning the data back from the far end. This command triggers an SPI transfer, returning the data back from the far end.
As an example (with MOSI looped back to MISO)::
As an example you can exchange (send and receive) 4 bytes (-x 4) on SPI2 (-b 2) using the command below with the ``loopback`` approach.
This approach requires that you connect the MOSI pin directly to the MISO pin (NOTE: SCLK and CS are not directly involved, but you still can see the clock and chip select waveforms if you decide to use an oscilloscope or more properly a logic analyzer to analyze these pins)::
nsh> spi exch -b 2 -x 4 aabbccdd nsh> spi exch -b 2 -x 4 aabbccdd
@@ -221,7 +223,7 @@ As an example (with MOSI looped back to MISO)::
Note that the ``TX Data`` are always specified in hex, and are always two digits Note that the ``TX Data`` are always specified in hex, and are always two digits
each, case insensitive. each, case insensitive.
I2C Build Configuration SPI Build Configuration
----------------------- -----------------------
NuttX Configuration Requirements NuttX Configuration Requirements
@@ -241,7 +243,7 @@ The SPI tools requires the following in your NuttX configuration:
CONFIG_SPI_DRIVER=y CONFIG_SPI_DRIVER=y
The SPI tool will then use the SPI character driver to access the SPI bus. The SPI tool will then use the SPI character driver to access the SPI bus.
These devices will reside at ``/dev/spiN`` where ``N`` is the I2C bus number. These devices will reside at ``/dev/spiN`` where ``N`` is the SPI bus number.
**Note**: The SPI driver ``ioctl`` interface is defined in **Note**: The SPI driver ``ioctl`` interface is defined in
``include/nuttx/spi/spi.h``. ``include/nuttx/spi/spi.h``.