README
^^^^^^

This directory contains various device drivers -- both block and
character drivers as well as other more specialized drivers.

Contents:
- Files in this directory
- Subdirectories of this directory
- Skeleton files

Files in this directory
^^^^^^^^^^^^^^^^^^^^^^^

can.c
This is a CAN driver. See include/nuttx/can.h for usage information.

dev_null.c and dev_zero.c
These files provide the standard /dev/null and /dev/zero devices.
See include/nuttx/fs/fs.h for functions that should be called if you
want to register these devices (devnull_register() and
devzero_register()).

loop.c
Supports the standard loop device that can be used to export a
file (or character device) as a block device. See losetup() and
loteardown() in include/nuttx/fs/fs.h.

pwm.c
Provides the "upper half" of a pulse width modulation (PWM) driver.
The "lower half" of the PWM driver is provided by device-specific
logic. See include/nuttx/pwm.h for usage information.

ramdisk.c
Can be used to set up a block of memory or (read-only) FLASH as
a block driver that can be mounted as a files system. See
include/nuttx/ramdisk.h.

ramlog.c
This is a driver that was intended to support debugging output,
aka syslogging, when the normal serial output is not available.
For example, if you are using a telnet or USB serial console,
the debug output will get lost.

This driver is similar to a pipe in that it saves the debugging
output in a FIFO in RAM. It differs from a pipe in numerous
details as needed to support logging.

This driver is built when CONFIG_RAMLOG is defined in the Nuttx
configuration.

rwbuffer.c
A facility that can be use by any block driver in-order to add
writing buffering and read-ahead buffering.

Subdirectories of this directory:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

analog/
This directory holds implementations of analog device drivers.
This includes drivers for Analog to Digital Conversion (ADC) as
well as drivers for Digital to Analog Conversion (DAC).
See include/nuttx/analog/*.h for registration information.

bch/
Contains logic that may be used to convert a block driver into
a character driver. This is the complementary conversion as that
performed by loop.c. See include/nuttx/fs/fs.h for registration
information.

input/
This directory holds implementations of input device drivers.
This includes such things as touchscreen and keypad drivers.
See include/nuttx/input/*.h for registration information.

lcd/
Drivers for parallel and serial LCD and OLED type devices. These
drivers support interfaces as defined in include/nuttx/lcd/lcd.h

mmcsd/
Support for MMC/SD block drivers. MMC/SD block drivers based on
SPI and SDIO/MCI interfaces are supported. See include/nuttx/mmcsd.h
and include/nuttx/sdio.h for further information.

mtd/
Memory Technology Device (MTD) drivers. Some simple drivers for
memory technologies like FLASH, EEPROM, NVRAM, etc. See
include/nuttx/mtd.h

(Note: This is a simple memory interface and should not be
confused with the "real" MTD developed at infradead.org. This
logic is unrelated; I just used the name MTD because I am not
aware of any other common way to refer to this class of devices).

net/
Network interface drivers. See also include/nuttx/net/net.h

pipes/
FIFO and named pipe drivers. Standard interfaces are declared
in include/unistd.h

power/
Power management (PM) driver interfaces. These interfaces are used
to manage power usage of a platform by monitoring driver activity
and by placing drivers into reduce power usage modes when the
drivers are not active.

sensors/
Drivers for various sensors

sercomm/
Sercomm is the transport used by osmocom-bb that runs on top of serial.
See http://bb.osmocom.org/trac/wiki/nuttx-bb/run for detailed the usage
of nuttx with sercomm.

drivers/sercomm is only built if CONFIG_SERCOMM_CONSOLE in the NuttX
configuration file. If you attempt to build this driver without
osmocom-bb, you will get compilation errors because of header files
that are needed from the osmocom-bb.

serial/
Front-end character drivers for chip-specific UARTs. This provide
some TTY-like functionality and are commonly used (but not required for)
the NuttX system console. See also include/nuttx/serial/serial.h

usbdev/
USB device drivers. See also include/nuttx/usb/usbdev.h

usbhost/
USB host drivers. See also include/nuttx/usb/usbhost.h

wireless/
Drivers for various wireless devices.

Skeleton Files
^^^^^^^^^^^^^^

Skeleton files a "empty" frameworks for NuttX drivers. They are provided to
give you a good starting point if you want to create a new NuttX driver.
The following skeleton files are available:

drivers/lcd/skeleton.c -- Skeleton LCD driver
drivers/mtd/skeleton.c -- Skeleton memory technology device drivers
drivers/net/skeleton.c -- Skeleton network/Ethernet drivers
drivers/usbhost/usbhost_skeleton.c -- Skeleton USB host class driver