We know already wether we start from a pause or not, so let's
take advantage of this knowledge instead of checking for
plausibility of a timer delay at interrupt time.
Costs just 8 bytes binary size:
SIZES ARM... lpc1114
FLASH : 7764 bytes 24%
RAM : 960 bytes 24%
EEPROM : 0 bytes 0%
Due to the less code at interrupt time, maximum step rate was
raised from 127.9 kHz to 130.6 kHz.
As dda_clock() is potantially too slow for high step rates, we
call it with a secondary interrupt with slightly slower priority.
This makes sure the slow part is ignored on high system load,
still reasonably synchonized with the clock tick.
Test: steppers should move and accelerate now.
Current binary size:
SIZES ARM... lpc1114
FLASH : 7756 bytes 24%
RAM : 960 bytes 24%
EEPROM : 0 bytes 0%
Works nicely, much less code than on AVR, because we have 32-bit
hardware timers.
Test: steppers should move. Only slowly, because dda_clock() isn't
called, yet, so no acceleration.
Pulse time on the Debug LED is 5.21 us or 250 clock ticks.
This test code in SysTickHanlder() should give you a rather
accurate clock with only a few seconds deviation per hour:
#include "serial.h"
#include "sersendf.h"
void SysTick_Handler(void) {
static uint32_t count = 0;
static uint8_t minutes = 0, seconds = 0;
count++;
if ( ! (count % 500)) { // A full second.
seconds++;
if ( ! (seconds % 60)) {
seconds = 0;
minutes++;
}
sersendf_P(PSTR("%su:"), minutes);
if (seconds < 10)
serial_writechar('0');
sersendf_P(PSTR("%su\n"), seconds);
}
[...]
Markus Hitter