==== GPIO bit-bang driver for Linux ====

The GPIO bit-bang driver creates an interface to Linux GPIOs using the IOCTL API.

Basic 1-bit input and output is available along with accelerated multiple bit shift I/O.

GPIO bit-bang is well suited to PICMicro ICSP but not exclusively.

=== Build ===

This module is built out of kernel and depends on the header files and tools found locally or may be cross compiled.

For cross compilation, an example Makefile named `cross-compile.mk' is provided which should work for Raspberry PI OS as explained [[:tools:raspbian#kernel|here]].

If the linux source directory was cross compiled and then copied to the target system to build the module, `scripts.sh' is provided to rebuild certain kernel header scripts locally. This is needed because some scripts are actually binary files on the foreign architecture.



=== Raspberry Pi OS===

First install development tools and the kernel headers when using a regular kernel.
<code>
apt-get install raspberrypi-kernel-headers
</code>

If you updated the kernel with rpi-update, install [[https://github.com/RPi-Distro/rpi-source|rpi-source]]

Now install headers for kernel installed with rpi-update.
<code>
rpi-source --skip-space
</code>

Now install the kernel module.
<code>
hg clone http://hg.kewl.org/pub/gpio-bb
cd gpio-bb
make
make install
</code>

=== Armbian ===

==BPI==

<code>
apt install linux-headers-current-sunxi
hg clone http://hg.kewl.org/pub/gpio-bb
cd gpio-bb
make
make install
</code>

=== Configuration ===
Update the modprobe configuration to create the gpio-bb device node when the module is loaded. For example, add the following to /etc/modprobe.d/modprobe.conf
<code>
install gpio-bb modprobe --ignore-install gpio-bb && modprobe gpio-bb && mknod /dev/gpio-bb c 180 0 && chmod 666 /dev/gpio-bb
</code>
Lastly, add the following to /etc/modules and reboot.
<code>
gpio-bb
</code>

=== Obsolete documentation ===
[[projects:gpio-bb:armbian|Armbian]]
[[projects:gpio-bb:bananian|Bananian]]
[[projects:gpio-bb:openwrt|OpenWRT]]
[[projects:gpio-bb:raspbian|Raspbian]]

=== Troubleshooting ===

gpio-bb uses the kernel API to access pins, this API demands exclusive access to a pin per process. This means you cannot use gpio-bb and sysfs export simultaneously for a single pin.

=== Resources ===

[[https://www.pedalpc.com/blog/program-pic-raspberry-pi/#gpio-bb|Using gpio-bb]]