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N_Cook N_Cook is offline
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Default Help hacking a laser tape measure?

On 06/08/2019 17:26, N_Cook wrote:
On 06/08/2019 16:18, wrote:
On Tuesday, 6 August 2019 13:36:38 UTC+1, wrote:
Some of us have time on our hands.
Some of us have a perverse level of curiosity.
Which leads some of us to do strange things for no apparent reason.

Peter Wieck
Melrose Park, PA


There is always a reason. The OP has not stated his.


A side-scan tide gauge (Google for one of those) Where no resident's
land is anywhere near the river water at low tide, just the top of the
tide. But 100m off land is about 98% of all the tide range , with large
collector lens (with bored=thru central hole for the outgoing laser )
works in lash-up so far. And unusually for tide gauges any wave action
increases the valid responses to the receiver at the required acute
angle. In line bright sunlight at 100m will probably be out though. Tide
height is then inversely proportional to the measured distance, as long
as the waves are not too high but that would just give a spread of
heights, averaging to about true presumably oe t least offsettable. A
"proper" geodometer with interface topc is far too expensive for this
sort of project.



Decoding so far, for anyone else doing similar (J makes an ideal search
engine term along with SZYCLCD.COM and ident YGFB178004-A1). 12MHz
sampling and 20 M samples per run on the analyser with d0 line for
trigger. SPI protocol with d3 as clock,d0 as MISO, d4 as MOSI, 4 bit
word length so superfluous analyser 8bit zeros removed in the following.
d1 and d2 only active during power-up page , not in measure mode.
For clarity and reduction, repeats in the coding via the following
look-up table.

J=
4,F,D,8,8,D,D,4,1,E,8,C,6,0,C,2,A,0,2,0,5,0,9,2,C, B,1,1,1,1,1,1,1,1,6,0,7,C,8,0,0,0,
K= 3,0,0,0,0,0,0,0,0,0,0,0,0,0,
L= 2,0,0,0,4,0,7,0,8,0,0,8,
N=2,0,A,0,0,8,4,0,8,0,0,4,
P=0,0,0,0,0,0,0,0,8,0,0,0,
Q=8,A,0,0,0,8,F,0,8,0,0,C,
R=0,0,4,0,5,0,8,0,0,8,
S=1,0,0,8,4,0,8,0,0,4,
T=1,0,0,8,F,0,8,0,0,C,
U=0,0,0,0,0,0,

Assuming J is invariant for this make and model in question, about 20
readings so far in the 1.000 to 2.000 display range ,it is invariant,
L to U would contain variation for units ,hundreds and thousands, DPs
and nulls and probably annunciators and other display rows data for the
other 3 lines in the display.

Single example of coding for the reading 1.264 in the bottom line for
the frames sent on pressing "measure" , running the analyser after
power-up each time and d0 line trigger occuring after pressing "measure"
, second frame is repeat of the first, powering down the measurer after
each reading.
1.264
J,K
L,K
N,K
Q,K
P,K
2,D,R,K
6,B,S,K
C,E,T,K
8,7,U,
J,K
2,D,R,K
6,B,S,K
C,E,T,K
8,7,U,

Preliminary decoding for readings in the range 1.0.. to 1.7..
for tenths in the rank P,K,*,x,R,K,*.y,S,K after the primary ident J,
where * is don't care/ignored and x,y is the coding
2 on the LCD codes to (x,y) D,B in the SPI
3 ~ D,7
5 ~ D,5
6 ~ D,D
7~ 9,7

for hundredths,
only *.*5* and *.*6* measures in the display so far
in the rank T,K,*,x,U
5 ~ SPI F
6 ~ 7
will probably require 1 or 2 other elements for the full set 0 to 9

for thousandths (for eventual use thousandths [mm] would be redundent)
R,K,x,*,S,K,y,*,T,K,z,*U
x, y, z SPI
1~ 6, 4, 0
2~ A, C, 4
3~ 6, C, 4
4~ 6, C, 8
6~ E, 8, C
7~ 6, 4, 4
8~ E, C, C


I might hookup an Arduino or a Pi , as in the intended usage , rather
than analyser ,for easier taking of pairs of readings/ LCD display
decoding look-up table determination , for the full set. There may be
transcription errors in the above of course.



--
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