kicad/scripts/ddr3_length_match.py

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#!/usr/bin/env python2
# Author: Dick Hollenbeck
# Report any length problems pertaining to a SDRAM DDR3 T topology using
# 4 memory chips: a T into 2 Ts routing strategy from the CPU.
# Designed to be run from the command line in a process separate from pcbnew.
# It can monitor writes to disk which will trigger updates to its output, or
# it can be run with --once option.
from __future__ import print_function
import pcbnew
import os.path
import sys
import time
CPU_REF = 'U7' # CPU reference designator
# four SDRAM memory chips:
DDR_LF = 'U15' # left front DRAM
DDR_RF = 'U17' # right front DRAM
DDR_LB = 'U16' # left back DRAM
DDR_RB = 'U18' # right back DRAM
# Length of SDRAM clock, it sets the maximum or equal needed for other traces
CLOCK_LEN = pcbnew.FromMils( 2.25 * 1000 )
def addr_line_netname(line_no):
"""From an address line number, return the netname"""
netname = '/DDR3/DRAM_A' + str(line_no)
return netname
# Establish GOALS which are LENs, TOLERANCEs and NETs for each group of nets.
# Net Group: ADDR_AND_CMD
ADDR_AND_CMD_LEN = pcbnew.FromMils( 2.22 * 1000 )
ADDR_AND_CMD_TOLERANCE = pcbnew.FromMils( 25 ) / 2
ADDR_AND_CMD_NETS = [addr_line_netname(a) for a in range(0,16)]
ADDR_AND_CMD_NETS += [
'/DDR3/DRAM_SDBA0',
'/DDR3/DRAM_SDBA1',
'/DDR3/DRAM_SDBA2',
'/DDR3/DRAM_RAS_B',
'/DDR3/DRAM_CAS_B',
'/DDR3/DRAM_WE_B'
]
# Net Group: CONTROL
CONTROL_LEN = pcbnew.FromMils( 2.10 * 1000 )
CONTROL_TOLERANCE = pcbnew.FromMils( 50 ) / 2
CONTROL_NETS = [
'/DDR3/DRAM_SDODT0',
#'/DDR3/DRAM_SDODT1',
'/DDR3/DRAM_CS0_B',
#'/DDR3/DRAM_CS1_B',
'/DDR3/DRAM_SDCKE0',
#'/DDR3/DRAM_SDCKE1',
]
BRIGHTGREEN = '\033[92;1m'
GREEN = '\033[92m'
BRIGHTRED = '\033[91;1m'
RED = '\033[91m'
ENDC = '\033[0m'
pcb = None
nets = None
dbg_conn = False # when true prints out reason for track discontinuity
def print_color(color, s):
print(color + s + ENDC)
def addr_line_netname(line_no):
netname = '/DDR3/DRAM_A' + str(line_no)
return netname
def pad_name(pad):
return str( pad.GetParent().Reference().GetShownText() ) + '/' + pad.GetPadName()
def pad_pos(pad):
return str(pad.GetPosition())
def pads_in_net(netname):
byname = {}
pads = nets[netname].Pads()
for pad in pads:
byname[pad_name(pad)] = pad
return byname
def track_ends(track):
"""return a string showing both ends of a track"""
return str(track.GetStart()) + ' ' + str(track.GetEnd())
def print_tracks(net_name,tracks):
print('net:', net_name)
for track in tracks:
print(' track:', track_ends(track))
def sum_track_lengths(point1,point2,netcode):
tracks = pcb.TracksInNetBetweenPoints(point1, point2, netcode)
sum = 0
for t in tracks:
sum += t.GetLength()
return sum
def tracks_in_net(netname):
nc = pcb.GetNetcodeFromNetname(netname)
tracks_and_vias = pcb.TracksInNet(nc)
# remove vias while making new non-owning list
tracks = [t for t in tracks_and_vias if not t.Type() == pcbnew.PCB_VIA_T]
return tracks
def print_pad(pad):
print( " pad name:'%s' pos:%s" % ( pad_name(pad), pad_pos(pad) ) )
def print_pads(prompt,pads):
print(prompt)
for pad in pads:
print_pad(pad)
def is_connected(start_pad, end_pad):
"""
Return True if the two pads are copper connected only with vias and tracks
directly and with no intervening pads, else False.
"""
netcode = start_pad.GetNet().GetNet()
try:
tracks = pcb.TracksInNetBetweenPoints(start_pad.GetPosition(), end_pad.GetPosition(), netcode)
except IOError as ioe:
if dbg_conn: # can be True when wanting details on discontinuity
print(ioe)
return False
return True
def find_connected_pad(start_pad, pads):
for p in pads:
if p == start_pad:
continue
if is_connected(start_pad,p):
return p
raise IOError( 'no connection to pad %s' % pad_name(start_pad) )
def find_cpu_pad(pads):
for p in pads:
if CPU_REF in pad_name(p):
return p
raise IOError( 'no cpu pad' )
def report_teed_lengths(groupname, netname, target_length, tolerance):
global dbg_conn
print(groupname, netname)
nc = pcb.GetNetcodeFromNetname(netname)
#print("nc", nc)
pads = nets[netname].Pads()
# convert from std::vector<> to python list
pads = list(pads)
#print_pads(netname, pads )
cpu_pad = find_cpu_pad(pads)
pads.remove(cpu_pad)
# a trap for a troublesome net that appears to be disconnected or has stray segments.
if netname == None:
#if netname == '/DDR3/DRAM_SDCKE0':
dbg_conn = True
# find the first T
#print_pads(netname + ' without cpu pad', pads )
t1 = find_connected_pad(cpu_pad, pads)
pads.remove(t1)
# find 2 second tier T pads
t2_1 = find_connected_pad(t1, pads)
pads.remove(t2_1)
t2_2 = find_connected_pad(t1, pads)
pads.remove(t2_2)
cpad = [0] * 4
# find 4 memory pads off of each 2nd tier T
cpad[0] = find_connected_pad(t2_1, pads)
pads.remove(cpad[0])
cpad[1] = find_connected_pad(t2_1, pads)
pads.remove(cpad[1])
cpad[2] = find_connected_pad(t2_2, pads)
pads.remove(cpad[2])
cpad[3] = find_connected_pad(t2_2, pads)
pads.remove(cpad[3])
len_t1 = sum_track_lengths(cpu_pad.GetPosition(),t1.GetPosition(),nc)
#print("len_t1 %.0f" % len_t1)
len_t2_1 = sum_track_lengths(t1.GetPosition(),t2_1.GetPosition(),nc)
len_t2_2 = sum_track_lengths(t1.GetPosition(),t2_2.GetPosition(),nc)
#print("len_t2_1 %.0f" % len_t2_1)
#print("len_t2_2 %.0f" % len_t2_2)
lens = [0] * 4
lens[0] = sum_track_lengths(t2_1.GetPosition(),cpad[0].GetPosition(),nc)
lens[1] = sum_track_lengths(t2_1.GetPosition(),cpad[1].GetPosition(),nc)
lens[2] = sum_track_lengths(t2_2.GetPosition(),cpad[2].GetPosition(),nc)
lens[3] = sum_track_lengths(t2_2.GetPosition(),cpad[3].GetPosition(),nc)
"""
for index, total_len in enumerate(lens):
print( "%s: %.0f" % (pad_name(cpad[index]), lens[index]))
"""
# Each net goes from CPU to four memory chips, these are the 4 lengths from
# CPU to each of the for memory chip balls/pads, some of these journies are
# common with one another but branch off at each T.
lens[0] += len_t1 + len_t2_1
lens[1] += len_t1 + len_t2_1
lens[2] += len_t1 + len_t2_2
lens[3] += len_t1 + len_t2_2
for index, total_len in enumerate(lens):
delta = total_len - target_length
if delta > tolerance:
print_color( BRIGHTRED, "%s %s len:%.0f long by %.0f mils" %
(netname, pad_name(cpad[index]), pcbnew.ToMils(total_len), pcbnew.ToMils(delta - tolerance) ))
elif delta < -tolerance:
print_color( BRIGHTRED, "%s %s len:%.0f short by %.0f mils" %
(netname, pad_name(cpad[index]), pcbnew.ToMils(total_len), pcbnew.ToMils(tolerance - delta) ))
def load_board_and_report_lengths(filename):
global pcb
pcb = pcbnew.LoadBoard(filename)
pcb.BuildListOfNets() # required so 'pcb' contains valid netclass data
global nets
nets = pcb.GetNetsByName()
for netname in ADDR_AND_CMD_NETS:
report_teed_lengths("addr_and_cmd", netname, ADDR_AND_CMD_LEN, ADDR_AND_CMD_TOLERANCE)
for netname in CONTROL_NETS:
report_teed_lengths("control", netname, CONTROL_LEN, CONTROL_TOLERANCE)
if __name__ == "__main__":
try:
boardfile = sys.argv[1]
except IndexError:
print("Usage: %s <boardname.kicad_pcb> [--once]" % sys.argv[0])
sys.exit(1)
first = True
while True:
# wait for the file contents to change
lastmtime = os.path.getmtime(boardfile)
mtime = lastmtime
while mtime == lastmtime and not first:
try:
mtime = os.path.getmtime(boardfile)
except OSError:
pass # kicad save process seems to momentarily delete file, so there's a race here with "No such file.."
time.sleep(0.5)
# The "Debug" build of pcbnew writes to disk slowy, new file takes time to get to disk.
time.sleep(1)
first = False
print( '\033[2J' ) # clear screen, maybe
load_board_and_report_lengths(boardfile)
if "--once" in sys.argv:
sys.exit(0)