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Merge pull request #106 from bgamari/Marlin_v1

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Make F_CPU dependence of stepper.cpp more explicit
This commit is contained in:
ErikZalm 2012-03-11 01:48:30 -08:00
commit 7cefad3744
3 changed files with 65 additions and 2 deletions
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6
Marlin/Makefile
View File

@ -23,7 +23,9 @@
# 3. Set the line containing "MCU" to match your board's processor.
# Older one's are atmega8 based, newer ones like Arduino Mini, Bluetooth
# or Diecimila have the atmega168. If you're using a LilyPad Arduino,
# change F_CPU to 8000000.
# change F_CPU to 8000000. If you are using Gen7 electronics, you
# probably need to use 20000000. Either way, you must regenerate
# the speed lookup table with create_speed_lookuptable.py.
#
# 4. Type "make" and press enter to compile/verify your program.
#
@ -42,6 +44,8 @@ MCU = atmega1280
#Arduino install directory
INSTALL_DIR = ../../arduino-0022/
# Be sure to regenerate speed_lookuptable.h with create_speed_lookuptable.py
# if you are setting this to something other than 16MHz
F_CPU = 16000000
UPLOAD_RATE = 115200

53
Marlin/create_speed_lookuptable.py Executable file
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@ -0,0 +1,53 @@
#!/usr/bin/env python
""" Generate the stepper delay lookup table for Marlin firmware. """
import argparse
__author__ = "Ben Gamari <bgamari@gmail.com>"
__copyright__ = "Copyright 2012, Ben Gamari"
__license__ = "GPL"
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument('-f', '--cpu-freq', type=int, default=16, help='CPU clockrate in MHz (default=16)')
parser.add_argument('-d', '--divider', type=int, default=8, help='Timer/counter pre-scale divider (default=8)')
args = parser.parse_args()
cpu_freq = args.cpu_freq * 1000000
timer_freq = cpu_freq / args.divider
print "#ifndef SPEED_LOOKUPTABLE_H"
print "#define SPEED_LOOKUPTABLE_H"
print
print '#include "Marlin.h"'
print
# Based on timer calculations of 'RepRap cartesian firmware' by Zack
# Smith and Philip Tiefenbacher.
print "const uint16_t speed_lookuptable_fast[256][2] PROGMEM = {"
a = [ timer_freq / ((i*256)+32) for i in range(256) ]
b = [ a[i] - a[i+1] for i in range(255) ]
b.append(b[-1])
for i in range(32):
print " ",
for j in range(8):
print "{%d, %d}," % (a[8*i+j], b[8*i+j]),
print
print "};"
print
print "const uint16_t speed_lookuptable_slow[256][2] PROGMEM = {"
a = [ timer_freq / ((i*8)+32) for i in range(256) ]
b = [ a[i] - a[i+1] for i in range(255) ]
b.append(b[-1])
for i in range(32):
print " ",
for j in range(8):
print "{%d, %d}," % (a[8*i+j], b[8*i+j]),
print
print "};"
print
print "#endif"

8
Marlin/stepper.cpp
View File

@ -750,7 +750,13 @@ void st_init()
// output mode = 00 (disconnected)
TCCR1A &= ~(3<<COM1A0);
TCCR1A &= ~(3<<COM1B0);
TCCR1B = (TCCR1B & ~(0x07<<CS10)) | (2<<CS10); // 2MHz timer
// Set the timer pre-scaler
// Generally we use a divider of 8, resulting in a 2MHz timer
// frequency on a 16MHz MCU. If you are going to change this, be
// sure to regenerate speed_lookuptable.h with
// create_speed_lookuptable.py
TCCR1B = (TCCR1B & ~(0x07<<CS10)) | (2<<CS10);
OCR1A = 0x4000;
TCNT1 = 0;