This should make the software I2C driver more portable, and potentially
usable on chips that aren't yet supported. More importantly, it avoids
some guesswork in the various chip-specific timing code.
This is implemented in inline assembly using machine.CPUFrequency() to
know how long a single CPU cycle takes. As long as it is called with a
constant duration, it should be fully inlined and all values can be
const-propagated resulting in very tight inline assembly.
For example, when I convert i2csoft to use this delay function, the
entire delay function compiles to something like this:
8784: movs r6, #100
8786: mov r0, r6
8788: nop
878a: nop
878c: nop
878e: nop
8790: nop
8792: subs r0, #1
8794: bne 0x8788
That means that all the math to calculate the number of cycles is
entirely optimized away (in this case, to 100 loops).
I ran the example on a few boards to see how well it works:
| board | 100ms wait | CPU core
|-----------------------|------------|------
| microbit | 121.6ms | Cortex-M0 so it has 12% overhead
| circuitplay-express | 100.1ms | Cortex-M0+ so it is cycle accurate
| pico | 100.2ms | Cortex-M0+
| pyportal | 100.3ms | Cortex-M4
| circuitplay-bluefruit | 125.8ms | Cortex-M4
| esp8266 | 125.1ms |
This shows that there is some loop overhead because of conservative
estimates, but note that even though there may be a 25% overhead, the
actual overhead per `delay.Sleep()` call is very small. It should be
good enough for software I2C at least, and can potentially be improved
in the future.
This speeds up the smoke tests by over 5x on my laptop, but keeps two
features that I find very important:
1. A stable output, which is used by tools like sizediff.
2. An easy to change text file with all the smoke tests.
This means that parsing is a little bit harder, but with the help of
packages like shlex and flag this is actually not very difficult.
It is needed to control the chip select pin when the st7789 display is
wired together with some other SPI device on the same bus, for example
if it shares the bus with SPI flash.
This required some refactoring of the code to correctly set the CS pin
everywhere. Notably, this removes the public Command, Data, Tx, and Rx
methods which poke into private details of the st7789 driver and are
therefore best hidden in my opinion.
* Unify the Rotation type, so that SetRotation can be used in
interfaces.
* Add Rotation() method to these displays, so that the current
rotation can be read.
* Change SetRotation() so that it can return an error (if the given
rotation isn't supported).
The API looks like this and is based on the PCA9685 PWM chip:
Sleep(sleepEnabled bool) error
It will set the LCD panel to a low power state (not displaying any
image) but memory contents will be preserved.
Heap allocations can result in significant and unpredictable slowdowns.
For example, they can take over 10ms on the Gopher Badge, which results
in visible tearing (when tearing is otherwise avoided).
Some displays need other values than the default to look right.
Therefore, add a configuration option to set the gamma table for a
particular LCD panel.
This is needed for high performance graphics.
Using this API, and using partial updates to the screen (no full screen
refreshes), I've been able to get well over 60fps of updates.
The current code interprets the 'century' flag as the year 2100. However the
DS3231 hardware does not incorporate this flag in its leap year calculation, so
will incorrectly consider the year 2100 as a leap year and increment from
2100-02-28 to 2100-02-29 instead of the correct 2100-03-01.
The 'century' bit is not useful for anything as far as I can tell. But instead
of removing the code that uses the 'century' bit, I thought it would be less
intrusive to just document the current behavior.
I also verified my interpretation of the DS3231 datasheet and my implementation
of this formula by placing a DS3231 chip in the freezer section of my
refrigerator for an hour or two, then reading the temperature. I got -16C,
which is close enough to the -18C that the freezer was set to.
- Remove all default loraconf default initialisation in lorawan examples (Region Settings takes care of this now)
- Remove retries while receiving JoinAccept and increase LoraRX to 10s (no need to wait more than 10s)
- Add constants for RegionSetting default frequencies
- Standardize all lora default configurations in lora examples
- Add new AT+LW=NET,(ON|OFF) command in atcmd example
deadprogram
Ayke van Laethem
Patricio Whittingslow
Daniel Esteban
Pablo Canseco
Daniel Esteban
Neil Davis
Brian Park
Olivier Fauchon
Olivier Fauchon