sergiotarxz/nuttx
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Doc: Fix broken SPI Tool documentation

Browse Source
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
Documentation/applications/system/spi/index.rst
View File

@ -2,7 +2,7 @@
``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.
Contents
@ -29,10 +29,10 @@ Contents
* ``set``
* ``verf``
- I2C Build Configuration
- SPI Build Configuration
* NuttX Configuration Requirements
* I2C Tool Configuration Options
* SPI Tool Configuration Options
System Requirements
-------------------
@ -71,7 +71,7 @@ or::
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,
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**:
- An environment variable like $PATH may be used for any argument.
- Arguments are _sticky_. For example, once the SPI address is specified, that
address will be re-used until it is changed.
- Arguments are _sticky_. For example, once the SPI bus is specified, that
bus will be re-used until it is changed.
**Warning**:
@ -117,7 +117,7 @@ SPI operation. Those arguments vary from command to command as described below.
However, there is also a core set of common ``OPTIONS`` supported by all commands.
So perhaps a better representation of the general SPI command would be::
i2c <cmd> [OPTIONS] [arguments]
spi <cmd> [OPTIONS] [arguments]
Where ``[OPTIONS]`` represents the common options and and arguments represent the
operation-specific arguments.
@ -146,7 +146,7 @@ Environment Variables
variables. Environment variables must be preceded with the special character
``$``. 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
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.
Common Option Summary
@ -187,7 +187,7 @@ Common Option Summary
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
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.
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
@ -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
each, case insensitive.
I2C Build Configuration
SPI Build Configuration
-----------------------
NuttX Configuration Requirements
@ -241,7 +243,7 @@ The SPI tools requires the following in your NuttX configuration:
CONFIG_SPI_DRIVER=y
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
``include/nuttx/spi/spi.h``.