This commit adds the class Linux::GPIO_Sysfs. This class provides a generic
implementation of AP_HAL::GPIO on Linux by using GPIO Sysfs Interface
(https://www.kernel.org/doc/Documentation/gpio/sysfs.txt).
The channel() interface should be preferred in places that need to be
fast. Since it maintains the file descriptor open this is much faster
than opening and closing it.
We are using a microcontroller to read the PWM input from RC. The read
values are sent to our board using a simple serial protocol through the
UART interface.
This patch interprets these values and passes them forward to the APM.
It uses a heating resistor controlled by a pwm.
By changing the duty cycle of the pwm, we can control the temperature.
A simple PI algorithm is used in order to get to the correct temperature
fast enough and without too much overshoot
It is implemented as a member of the Util class in order not to make to much
modification to the current codebase
ToneAlarm is now declared as a separate class instance of which is added as a private member of LinuxUtil
Some minor fixes in this patch include changing return type of tonealarm_init() to bool and use dprintf
Preliminary support for Zynq/Linux on the 'ZyboPilot' HW platform.
see https://github.com/trjw/ZyboPilot-bsp for the PetaLinux / Vivado project
files.
At this stage CPPM/Pulse in and PWM out work, and in CLI mode the passthru
test works correctly.
The platform has passed minimal smoke testing in HIL mode.
ZYNQ IS NOT FLIGHT TESTED YET! FLY THIS PLATFORM AT YOUR OWN RISK!
Signed-off-by: John Williams <john@whelanwilliams.net>