Die length doesn't seem to work

Software
1

I have set the die length on DDR3 interface pins and don’t see any change in the reported track lengths in either the bottom status info or the tune track length tool. Any ideas? I’m using BZR5591.

Below is a python script I wrote to add the die lengths from a CSV file:

#!/usr/bin/env python
# kicad file is first arg, csv of lengths is 2nd  
import sys, math
from pcbnew import *

c = 2.998e8 # speed of light (m/s)   
er = 4.3 # relative permittivity 
mm_per_m = 1000.0
s_per_ps = 1e-12

pcb = LoadBoard(sys.argv[1])

scale = c*mm_per_m*s_per_ps/math.sqrt(er) # have picoseconds, need mm                                                          
lengths = {}

with open(sys.argv[2]) as f:
    for l in f:
        d = l.split(',')
        lengths[d[0]] = float(d[1]) * scale

mod = pcb.FindModuleByReference('U1')
pads = mod.Pads()

for pad in pads:
    name = pad.GetPadName()
    if name in lengths:
        pad.SetPadToDieLength(FromMM(lengths[name]))

pcb.Save("./mod.kicad_pcb")
2

Working around this one with a script to dump track lengths on the DDR interface and other things that could benefit from length matching and add the pad to die length. Note the hard coded U1 that is the CPU. That is a bit of a hack.

#!/usr/bin/env python

import sys
from pcbnew import *

pcb = LoadBoard(sys.argv[1])
tracks = pcb.GetTracks()
td = {}
mod = pcb.FindModuleByReference('U1')
pads = mod.Pads()
for pad in pads:
    name = pad.GetNetname()
    length = ToMM(pad.GetPadToDieLength())
    td[name] = length

for track in tracks:
    name = track.GetNetname()
    length = ToMM(track.GetLength())
    if name in td:
        td[name] += length
    else:
        td[name] = length

addr = ['/dram/DDR_CK-',
        '/dram/DDR_CK+',
        '/dram/DDR_BA1',
        '/dram/DDR_BA0',
        '/dram/DDR_BA2',
        '/dram/DDR_A5',
        '/dram/DDR_CKE',
        '/dram/DDR_A12',
        '/dram/DDR_A13',
        '/dram/DDR_A10',
        '/dram/DDR_A14',
        '/dram/DDR_ODT',
        '/dram/DDR_A11',
        '/dram/DDR_RAS_B',
        '/dram/DDR_CAS_B',
        '/dram/DDR_A8',
        '/dram/DDR_A9',
        '/dram/DDR_A0',
        '/dram/DDR_A1',
        '/dram/DDR_A2',
        '/dram/DDR_A3',
        '/dram/DDR_A4',
        '/dram/DDR_A6',
        '/dram/DDR_A7',
        '/dram/DDR_WE_B',
        '/dram/DDR_CS_B']

dq0 = ['/dram/DDR_DQS0-',
       '/dram/DDR_DQS0+',
       '/dram/DDR_DQ6',
       '/dram/DDR_DQ3',
       '/dram/DDR_DQ2',
       '/dram/DDR_DQ1',
       '/dram/DDR_DQ0',
       '/dram/DDR_DQ7',
       '/dram/DDR_DQ5',
       '/dram/DDR_DQ4',
       '/dram/DDR_DM0']

dq1 = ['/dram/DDR_DQS1+',
       '/dram/DDR_DQS1-',
       '/dram/DDR_DQ9',
       '/dram/DDR_DQ8',
       '/dram/DDR_DQ13',
       '/dram/DDR_DQ12',
       '/dram/DDR_DQ11',
       '/dram/DDR_DQ10',
       '/dram/DDR_DQ15',
       '/dram/DDR_DQ14',
       '/dram/DDR_DM1']

def plist(nlist):
    count = 0
    length = 0
    for net in td:
        if not net in nlist:
            continue
        print net, td[net]
        count += 1
        length += td[net]
    print length/count

print "\ncontrol"
plist(addr)
print "\ndq0"
plist(dq0)
print "\ndq1"
plist(dq1)

print "\nDAC"
count = 0
length = 0
for net in td:
    if not "DACD" in net:
        continue
    print net, td[net]
    count += 1
    length += td[net]

print "\nRGMII"
count = 0
length = 0
for net in td:
    if not "/mio/ENET" in net:
        continue
    print net, td[net]
    count += 1
    length += td[net]