On 8/5/2019 10:56 AM, N_Cook wrote:
Firstly for anyone else playing with these neat cheap laser diode
measuring devices.
I'm initially playing with a (Lidl) Parkside PLEM 50 (50m range), to
eventuallyÂ* use a Lomvum LV 120 (120m range) coupled to a pc via
Pi/Arduino. Both have 4 line 7segment LCD plus annunciators display with
a "chip on glass" look-up page chip for decoding and driving the LCD.
Made by SZYCLCD.COM and ident YGFB178004-A1 on the .5mm spacing ribbon
and I know by swapping between each, they are compatible between both
devices , completely different external and internal appearance, but
same STM micro. 14 way ribbon to LCD , 2 w for backlight, 2w for power
to chip on glass and a number of apparently inactive lines in
measurement mode anyway . So d0 clock , d3 and d4 used for SPI update
principal lastline of LCD and d2 +d3 active during power-up/first page
but not in measure mode.
Breaking-out at the ZIF ribbon socket and using Hobbycomponents
"matchbox" pulse analyser and Sigrok/Pulseview and pairs of readings on
the lower line of the LCD, ie switch unit on, then just pressing
"measure" once initiates the SPI clock pulses. The LCD is updated from
switch-on display in 0.5 to 1 seconds , so the data must be contained
within the first 2 or 3 frames of data. Short duration bursts of clock
then various amounts of dead space , as much as 400mS between frames,
highly variable duration.
I was hoping the same as

https://www.mictronics.de/2018/02/la...-meter-hack/4/
LookupTableLcdLastLine.pdf , on link
https://www.mictronics.de/?wpfb_dl=156
on seeing 17 4 bit words per frame (mainly, sometimes 13, sometimes 16)
The first frame seems to have only 4 variants and is re-used for totally
different last-line readings. Whatever I set sampling speed, clock
polarity or phase etc I cannot avoid the "smearing" between frames ,eg
348-384 : 05
378-403 : 00
403-428 : 04

429-1961499 : 0C

980976-981002 : 0D
981001-981026 : 00
981026-981051 : 04

how to tidy up word apportionment ?.

And then for pairs of metre/mm distance readings I cannot get any sense
of pertinent words to decode/look-up (redundant 0's removed here for
linwrap)
and only frames 2 and 3 including the "smears"
B1820 sequence looked promising as an ident but non appearance in one
dataset.


00012080049008B180208010400A200Â* =6.345a
8B18020400108A000001208004900Â*Â*Â* =6.345b

8B180200010400A4000044041002101Â*Â* =5.085a
000120A000504CD0401048082004202Â*Â* =5.085b
(B18020 sequence not appearing in any succeeding frame, well beyond 1
second)

00012080049088B180208010400A404Â*Â* =1.564a
B180200010400A400008010400A404Â*Â*Â* =1.564b





What did he say?
Mikek