Goal is to calculate steps in a separate function to allow different
methods of steps calculation, which is neccessary for supporting
different kinematics types. Accordingly we have to calculate steps
for all axes before setting directions and such stuff.
This was the goal: to not bit-shift when calling setTimer(). Binary
size another 40 bytes off, about 1.2 % better performance:
SIZES ATmega... '168 '328(P) '644(P) '1280
FLASH : 20136 bytes 141% 66% 32% 16%
RAM : 2318 bytes 227% 114% 57% 29%
EEPROM: 32 bytes 4% 2% 2% 1%
short-moves.gcode statistics:
LED on occurences: 888.
LED on time minimum: 302 clock cycles.
LED on time maximum: 718 clock cycles.
LED on time average: 311.258 clock cycles.
smooth-curves.gcode statistics:
LED on occurences: 9124.
LED on time minimum: 307 clock cycles.
LED on time maximum: 708 clock cycles.
LED on time average: 357.417 clock cycles.
triangle-odd.gcode statistics:
LED on occurences: 1636.
LED on time minimum: 302 clock cycles.
LED on time maximum: 708 clock cycles.
LED on time average: 330.322 clock cycles.
Admittedly it looks like advancing in babysteps, but really
catching every bit shifting instance isn't trivial, sometimes
these shifts are already embedded in other calculations.
Still no binary size or performance change.
While this shifting meant to increase accuracy, there's no actual
use of it, other than that this value gets shifted back and forth.
Let's start to get rid of it.
Performance stays exactly the same:
SIZES ATmega... '168 '328(P) '644(P) '1280
FLASH : 20188 bytes 141% 66% 32% 16%
RAM : 2318 bytes 227% 114% 57% 29%
EEPROM: 32 bytes 4% 2% 2% 1%
short-moves.gcode statistics:
LED on occurences: 888.
LED on time minimum: 306 clock cycles.
LED on time maximum: 722 clock cycles.
LED on time average: 315.253 clock cycles.
smooth-curves.gcode statistics:
LED on occurences: 9124.
LED on time minimum: 311 clock cycles.
LED on time maximum: 712 clock cycles.
LED on time average: 361.416 clock cycles.
triangle-odd.gcode statistics:
LED on occurences: 1636.
LED on time minimum: 306 clock cycles.
LED on time maximum: 712 clock cycles.
LED on time average: 334.319 clock cycles.
This finally brings Z axis up to speed.
So far we always assumed the fastest axis to have the same steps/mm
as the X axis. In cases where this wasn't true, the movement
wouldn't do sufficient acceleration steps and, accordingly,
not reach the expected maximum speed. This was particularly visible
on a typical Mendel printer, where the Z axis would reach only a
6th of the commanded speed in some configurations.
'all_time' sounds like forever to me, but this variable really
tracks the last time we hit one of "all the axes". It sticks
out more now in looping, so rename it to make sense.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 9 is, finally use this set_direction() thing. As a dessert
topping, it reduces binary size by another 122 bytes.
SIZES ATmega... '168 '328(P) '644(P) '1280
FLASH : 19988 bytes 140% 66% 32% 16%
RAM : 2302 bytes 225% 113% 57% 29%
EEPROM: 32 bytes 4% 2% 2% 1%
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 8 is, move remaining update_current_position() into a loop.
This makes the binary 134 bytes smaller. As it's not critical,
no performance test.
SIZES ATmega... '168 '328(P) '644(P) '1280
FLASH : 20134 bytes 141% 66% 32% 16%
RAM : 2302 bytes 225% 113% 57% 29%
EEPROM: 32 bytes 4% 2% 2% 1%
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 7 is, turn update_current_position() in dda.c partially into
a loop. Surprise, surprise, this changes neither binary size nor
performance. Looking into the generated assembly, the loop is
indeed completely unrolled. Apparently that's smaller than a
real loop.
SIZES ATmega... '168 '328(P) '644(P) '1280
FLASH : 20270 bytes 142% 66% 32% 16%
RAM : 2302 bytes 225% 113% 57% 29%
EEPROM: 32 bytes 4% 2% 2% 1%
short-moves.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 888.
Sum of all LED on time: 279945 clock cycles.
LED on time minimum: 306 clock cycles.
LED on time maximum: 722 clock cycles.
LED on time average: 315.253 clock cycles.
smooth-curves.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 9124.
Sum of all LED on time: 3297806 clock cycles.
LED on time minimum: 311 clock cycles.
LED on time maximum: 712 clock cycles.
LED on time average: 361.443 clock cycles.
triangle-odd.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 1636.
Sum of all LED on time: 546946 clock cycles.
LED on time minimum: 306 clock cycles.
LED on time maximum: 712 clock cycles.
LED on time average: 334.319 clock cycles.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 6c removes do_step(), but still tries to keep a loop. This
about the maximum of performance I (Traumflug) can think of.
Binary size is as good as with the former attempt, but performance
is actually pretty bad, 45% worse than without looping:
SIZES ATmega... '168 '328(P) '644(P) '1280
FLASH : 19876 bytes 139% 65% 32% 16%
RAM : 2302 bytes 225% 113% 57% 29%
EEPROM: 32 bytes 4% 2% 2% 1%
short-moves.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 888.
Sum of all LED on time: 406041 clock cycles.
LED on time minimum: 448 clock cycles.
LED on time maximum: 864 clock cycles.
LED on time average: 457.253 clock cycles.
smooth-curves.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 9124.
Sum of all LED on time: 4791132 clock cycles.
LED on time minimum: 453 clock cycles.
LED on time maximum: 867 clock cycles.
LED on time average: 525.113 clock cycles.
triangle-odd.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 1636.
Sum of all LED on time: 800586 clock cycles.
LED on time minimum: 448 clock cycles.
LED on time maximum: 867 clock cycles.
LED on time average: 489.356 clock cycles.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 6b moves do_step() from the "tidiest" place into where it's
currently used, dda.c. Binary size goes down another 34 bytes, to
a total savings of 408 bytes and performance is much better, but
still 16% lower than without using loops:
SIZES ATmega... '168 '328(P) '644(P) '1280
FLASH : 19874 bytes 139% 65% 32% 16%
RAM : 2302 bytes 225% 113% 57% 29%
EEPROM: 32 bytes 4% 2% 2% 1%
short-moves.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 888.
Sum of all LED on time: 320000 clock cycles.
LED on time minimum: 351 clock cycles.
LED on time maximum: 772 clock cycles.
LED on time average: 360.36 clock cycles.
smooth-curves.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 9124.
Sum of all LED on time: 3875874 clock cycles.
LED on time minimum: 356 clock cycles.
LED on time maximum: 773 clock cycles.
LED on time average: 424.8 clock cycles.
triangle-odd.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 1636.
Sum of all LED on time: 640357 clock cycles.
LED on time minimum: 351 clock cycles.
LED on time maximum: 773 clock cycles.
LED on time average: 391.416 clock cycles.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 6a is putting stuff inside the step interrupt into a loop,
too. do_step() is put into the "tidiest" place. Binary size goes
down a remarkable 374 bytes, but stepping performance suffers by
almost 30%.
Traumflug's performance measurements:
SIZES ATmega... '168 '328(P) '644(P) '1280
FLASH : 19908 bytes 139% 65% 32% 16%
RAM : 2302 bytes 225% 113% 57% 29%
EEPROM: 32 bytes 4% 2% 2% 1%
short-moves.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 888.
Sum of all LED on time: 354537 clock cycles.
LED on time minimum: 390 clock cycles.
LED on time maximum: 806 clock cycles.
LED on time average: 399.253 clock cycles.
smooth-curves.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 9124.
Sum of all LED on time: 4268896 clock cycles.
LED on time minimum: 395 clock cycles.
LED on time maximum: 807 clock cycles.
LED on time average: 467.875 clock cycles.
triangle-odd.gcode
Statistics (assuming a 20 MHz clock):
LED on occurences: 1636.
Sum of all LED on time: 706846 clock cycles.
LED on time minimum: 390 clock cycles.
LED on time maximum: 807 clock cycles.
LED on time average: 432.057 clock cycles.
Should be done for temptable in ThermistorTable.h, too, but this
would mess up an existing users' configuration.
This tries to put emphasis on the fact that you have to read
these values with pgm_read_*() instead of just using the variable.
Unfortunately, gcc compiler neither inserts PROGMEM reading
instructions automatically when reading data stored in flash,
nor does it complain or warn about the missing read instructions.
As such it's very easy to accidently handle data stored in flash
just like normal data. It'll compile and work ... you just read
arbitrary data (often, but not always zeros) instead of what you
intend.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 5 is move ACCELERATION_TEMPORAL's step delay calculations
into loops. Not tested, binary size change unknown.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 4 is move ACCELERATION_TEMPORAL's maximum feedrate limitation
into a loop. Not tested, binary size change unknown.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 3 is moving fast axis detection into a loop.
Binary size 84 bytes smaller.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Part 2 is moving maximum speed limit calculations into loops.
Binary size another 160 bytes smaller.
Clean up code to reduce duplication by consolidating code into
loops for per-axis actions.
Traumflug notes:
Split this once huge commit into smaller ones for ease of
reviewing and bisecting (in case something went wrong).
Part 1 is to put dda_create() distance calculations into loops.
This reduces binary size by another whopping 756 bytes.
This was contributed by Phil Hord as part of another commit.
It saves 168 bytes, to it more than outweights the overhead of
introducing a generic implementation already.
Many places in the code use individual variables for int/uint values
for X, Y, Z, and E. A tip from a comment suggests making these into
arrays for scalability in the future. Replace the discrete variables
with arrays so the code can be simplified in the future.
In preparation for more efficient and scalable code using axis-loops
for common operations, add two new array-types for signed and unsigned
32-bit values per axis. Make the TARGET type use this array instead of
its current X, Y, Z, and E variables.
Traumflug notes:
- Did the usual conversion to spaces for changed lines.
- Added X = 0 to the enum. Just for peace of mind.
- Excellent patch!
Initially I wanted to make the new array an anonymous union with the
old variables to allow accessing values both ways. This way it would
have been possible to do the transition in smaller pieces. But as
the patch worked so flawlessly and binary size is precisely the
same, I abandoned this idea. Maybe it's a good idea in other areas.
This macro is pretty expensive (700 bytes, well, stuff is now
calculated at runtime), so there's no chance to use it in multiple
places and we likely also need this in dda_lookahead.c to achieve
full 4 axis compatibility there.
For now this is for the initial rampup calculation, only, notably
for moving the Z axis (which else gets far to few rampup steps on
a typical mendel-like printer).
The used macro was verified with this test code (in mendel.c):
[...]
int main (void) {
init();
uint32_t speed, spm;
char string[128];
for (spm = 2000; spm < 4099000; spm <<= 1) {
for (speed = 11; speed < 65536; speed *= 8) {
sersendf_P(PSTR("spm = %lu speed %lu ==> macro %lu "),
spm, speed, ACCELERATE_RAMP_LEN_SPM(speed, spm));
delay_ms(10);
sprintf(string, "double %f\n",
(double)speed * (double)speed / ((double)7200000 * (double)ACCELERATION / (double)spm));
serial_writestr((uint8_t *)string);
delay_ms(10);
}
}
[...]
Note: to link the test code, this linker flag is required to add
the full printf library (which does print doubles):
LDFLAGS += -Wl,-u,vfprintf -lprintf_flt -lm
Keeping the hack causes the previous move to decelerate, which isn't
intended when movements are joined with lookahead.
Removing only the hack breaks endstop handling on those axes which
set a huuuge number of acceleration steps for the lack of a proper
calculation algorithm. We have this algorithm now, so we can stop
using this kludge.
Solves part 1 of issue #68.
This is a preparation towards going through the existing movement
queue backwards with dda_join_moves() to allow higher feedrates
for lots of short movements.
This obviously requires less place on the stack and accordingly a
few CPU cycles less, but more importantly, it lets decide
dda_start() whether a previous movement is to be taken into account
or not.
To make this decision more reliable, add a flag for movements done.
Else it could happen we'd try to join with a movement done long
before.
In AVR the labs() function takes a 32-bit signed int parameter. On
the PC it's at least 64-bits and maybe more. When we have a 32-bit
unsigned value we're taking the labs() of, coercing it to 32-bits
first turns our high-bit into a sign, but coercing it to 64-bits
does not. This causes all our negative values to appear to be
really big positive ones.
Create a new function abs32() which always coerces its argument to
a int32_t first before return the abs value. Use that function
whereved needed in dda.c.
This fixes a problem on the simulator which caused negative
direction movements to "never" end.
This code was accidentally removed long ago in a botched merge. This
patch recovers it and makes it build again. I've done minimal testing
and some necessary cleanup. It compiles and runs, but it probably still
has a few dust bunnies here and there.
I added registers and pin definitions to simulator.h and
simulator/simulator.c which I needed to match my Gen7-based config.
Other configs or non-AVR ports will need to define more or different
registers. Some registers are 16-bits, some are 8-bit, and some are just
constant values (enums). A more clever solution would read in the
chip-specific header and produce saner definitions which covered all
GPIOs. But this commit just takes the quick and easy path to support my
own hardware.
Most of this code originated in these commits:
commit cbf41dd4ad
Author: Stephan Walter <stephan@walter.name>
Date: Mon Oct 18 20:28:08 2010 +0200
document simulation
commit 3028b297f3
Author: Stephan Walter <stephan@walter.name>
Date: Mon Oct 18 20:15:59 2010 +0200
Add simulation code: use "make sim"
Additional tweaks:
Revert va_args processing for AVR, but keep 'int' generalization
for simulation. gcc wasn't lying. The sim really aborts without this.
Remove delay(us) from simulator (obsolete).
Improve the README.sim to demonstrate working pronterface connection
to sim. Also fix the build instructions.
Appease all stock configs.
Stub out intercom and shush usb_serial when building simulator.
Pretend to be all chip-types for config appeasement.
Replace sim_timer with AVR-simulator timer:
The original sim_timer and sim_clock provided direct replacements
for timer/clock.c in the main code. But when the main code changed,
simcode did not. The main clock.c was dropped and merged into timer.c.
Also, the timer.c now has movement calculation code in it in some
cases (ACCELERATION_TEMPORAL) and it would be wrong to teach the
simulator to do the same thing. Instead, teach the simulator to
emulate the AVR Timer1 functionality, reacting to values written to
OCR1A and OCR1B timer comparison registers.
Whenever OCR1A/B are changed, the sim_setTimer function needs to be
called. It is called automatically after a timer event, so changes
within the timer ISRs do not need to bother with this.
A C++ class could make this requirement go away by noticing the
assignment. On the other hand, a chip-agnostic timer.c would help
make the main code more portable. The latter cleanup is probably
better for us in the long run.
This is a preparation for starting a move from non-zero speeds,
which is needed for look-ahead. Keeping both variables in
move_state and doing the calculations in dda_start() is possible
in principle, but might not fit the tight time budget we have when
going from one movement to the next at high step rates.
To deal with this, we have to pre-calculate n and c, so we have
to move it back into the DDA structure. It was there a year ago
already, but moved into move_state to save RAM (move_state exists
only once, dda as often as there are movement queue entries).
His implementation was done on every step and as it turns out,
the very same maths works just fine in the clock interrupt.
Reason for the clock interrupt is: it allows about 3 times
higher step rates.
This strategy is not only substantially faster, but also
a bit smaller.
One funny anecdote: the acceleration initialisation value, C0,
was taken from elsewhere in the code as-is. Still it had to be
adjusted by a factor of sqrt(2) to now(!) match the physics
formulas and to get ramps reasonably matching the prediction
(and my pocket calculator). Apparently the code before
accumulated enough rounding errors to compensate for the
wrong formula.
Before, endstops were checked on every step, wasting precious time.
Checking them 500 times a second should be more than sufficient.
Additionally, an endstop stop now properly decelerates the movement.
This is one important step towards handling accidental endstop hits
gracefully, as it avoids step losses in such situations.
This means, modify existing code to let the lookahead algorithms
do their work. It also means to remove some unused code in
dda_lookahead.c and reordering some code to make it work with
LOOKAHEAD undefined.
The binary size impact is moderate, like 18 bytes plus
4 bytes per endstop defined.
The story is a follows:
The endstop logic can be used to use a touch probe with PCB
milling. Connect the (conductive) PCB surface to GND, the
spindle/mill bit to the signal line, turn the internal pullups
on and there you go.
However, doing so with pullups always enabled and while milling
under (conductive) water showed polished mill and drill bits to
become matte after a few hours of usage. Obviously, this small
0.5 mA current from the pullup resistors going through the
rotating mill bit is sufficient to get some spark erosion going.
That's bad, as spark erosion happening also means tools become
dull faster than neccessary.
With this patch, pullups are turned on while being used, only,
so this sparc erosion should go away.
This gets rid of overflows at micrometer to step conversion as
much as possible within 31 bits. It also opens the door to get
STEPS_PER_M configurable at runtime.
This also costs 290 bytes, unfortunately.
These were commits 9dbfa7217e0de8b140846ab480d6b4a7fc9b6791 and
2b596cb05e621ed822071486f812eb334328267a.
There are several reasons why this new approach didn't work out well:
- The machine coordinate system is lost on relative movements.
OK, we could keep tracking it, but this would mean even more
code, so even more chances for bugs.
- With the lost coordinate system, no software endstops are possible.
- Neither of X, Y, Z will ever overflow.
- If a movement planner would appear one day, he'd have to handle
relative movements as well. Even more code duplication.
Instead of converting them to absolute first, then back to
relative and having all the fuzz with working on the queue's
start vs. working at the queue's end, mark a movement as relative
and use this directly.
The implementation is slightly different this time, as it's not
using these famous bresenham algorithms. The intention is to
allow axis-independent movements, as it's required for
EMC-quality look-ahead.
This makes the code cleaner and the reduction of code
probably easily compensates for keeping global interrupts
enabled for a bit longer. Talked to macscifi about this.
Saves about 300 bytes of binary size.
We want to stop stepping as there are no steps left, not one step later.
Accordingly, we get rid of a small pause between two movements and
also have to decelerate one step earlier.
This is a intrusive patch and for now, it's done for the X axis only.
To make comparison with the former approach easier ...
The advantages of this change:
- Converting from mm to steps in gcode_parse.c and back in dda.c
wastes cycles and accuracy.
- In dda.c, UM_PER_STEP simply goes away, so distance calculations
work now with STEPS_PER_MM > 500 just fine. 1/16 microstepping
on threaded rods (Z axis) becomes possible.
- Distance calculations (feedrate, acceleration, ...) become much
simpler.
- A wide range of STEPS_PER_M can now be handled at reasonable
(4 decimal digit) accuracy with a simple macro. Formerly,
we were limited to 500 steps/mm, now we can do 4'096 steps/mm
and could easily raise this another digit.
Disadvantages:
- STEPS_PER_MM is gone in config.h, using STEPS_PER_M is required,
because the preprocessor refuses to compare numbers with decimal
points in them.
- The DDA has to store the position in steps anyways to avoid
rounding errors.
Markus Hitter
Phil Hord
David Forrest
Roland Brochard
Ben Gamari