Instead of depending on the frequency accumulate() is called, use
AverageIntegralFilter with 10 samples. The data obtained by BMP085 is
too noisy with any value of OVERSAMPLING so use twice the number of
samples as currently used. Besides that now we are sure there's always
10 samples used in the average.
The temperature readings is not subject to white noise so there's no
point in averaging its reading. Moreover since for a normal 50Hz
accumulate() / 10Hz update() it would read temperature only once per
update(), it's pointless to keep averaging and introducing rounding
error.
The temperature doesn't need to be checked as frequent as pressure, too.
The datasheet even suggests on section 3.3, page 10 to enable standard
mode and read the temperature at 1Hz. Here we reduce it to 2Hz
(considering the accumulate() function being called at 50Hz).
If we don't have EOC pin and assuming the accumulate() function is
called at 50Hz (or higher) we would take very few samples to accumulate
before the update is called. That's because since we have to wait 26ms
to get a sample and we calling accumulate() every 20ms, half of the
times it will return without getting anything. So we will
be using 2 or 3 samples only to average.
If we don't have EOC, use OVERSAMPLING=2 which gives us more noise, but
that we can filter out by using measurements to average. When we have
EOC we don't need it because most of the time the conversion will take
less than 20ms: I'm getting 16ms on most of them while bench-testing.
We don't need to expose to other libraries how each backend is
implemented. AP_Baro.h is the main header, included by other libraries.
Instead of including each backend in the main header, move them to where
they are needed. Additionally standardize the order and how we include
the headers.
The advantages are:
- Internals of each backend is not exposed outside of the
library
- Faster incremental builds since we don't need to recompile
whoever includes AP_Baro.h because a backend changed
The configuration of MS5637 is different from MS5611 in 2 ways:
- The PROM is of 112 bytes rather than 128
- The CRC is located in the first MSB of the first word, not the
last one
For CRC calculation we also need to zero out the last (missing) word.
This renames _check_crc() to _read_prom(), which returns false when the
PROM doesn't contain valid data. It also makes it virtual so MS5637 can
override it. This also moves the PROM read to be all in the same place
rather than split between the CRC field and coefficient fields. Finally
calculate_crc() is renamed to crc4() to be shorter and add info on what
it does.
On MS5637 we will need to override the method to read and calculate the
PROM's crc. Thus we need a 2-phase init.
It also makes the constructor of AP_Baro_MS56XX protected since only the
derived classes should instantiate the base one.
This is the same change as done in PX4:
This reduces self-heating of the sensor which reduces the amount
of altitude change when warming up. Apparently some individual
sensors are severely affected by this.
Unfortunately it raises the noise level, but Paul is confident
it won't be a significant issue.
Remove the checks for HAL_CPU_CLASS > HAL_CPU_CLASS_16 and
HAL_CPU_CLASS >= HAL_CPU_CLASS_75. Corresponding dead code will be
removed on separate commits.
Now variables don't have to be declared with PROGMEM anymore, so remove
them. This was automated with:
git grep -l -z PROGMEM | xargs -0 sed -i 's/ PROGMEM / /g'
git grep -l -z PROGMEM | xargs -0 sed -i 's/PROGMEM//g'
The 2 commands were done so we don't leave behind spurious spaces.
AVR-specific places were not changed.
The PSTR is already define as a NOP for all supported platforms. It's
only needed for AVR so here we remove all the uses throughout the
codebase.
This was automated with a simple python script so it also converts
places which spans to multiple lines, removing the matching parentheses.
AVR-specific places were not changed.
Instead of requiring every program to specify the HAL related modules,
let the build system do it (in practice everything we compiled depended
on HAL anyway). This allow including only the necessary files in the
compilation.
The switching between different AP_HAL was happening by giving different
definitions of AP_HAL_BOARD_DRIVER, and the programs would use it to
instantiate.
A program or library code would have to explicitly include (and depend)
on the concrete implementation of the HAL, even when using it only via
interface.
The proposed change move this dependency to be link time. There is a
AP_HAL::get_HAL() function that is used by the client code. Each
implementation of HAL provides its own definition of this function,
returning the appropriate concrete instance.
Since this replaces the job of AP_HAL_BOARD_DRIVER, the definition was
removed.
The static variables for PX4 and VRBRAIN were named differently to avoid
shadowing the extern symbol 'hal'.
