I have built a system for my lathe using "Chinese" scales. If I connect my level shifter outputs to 2.1/2.4 and 2.2/2.3 on the MSP everything works well. If I connect the level shifted output of either scale to 2.0/2.5 the display is very erratic. As I move the reader head I may increment on the display but then suddenly show a totally different number. With continuing movement this may increment then suddenly change again. It does not matter which scale is connected to which level shifter, the problem solely relates to the "X" inputs. I am currently using Y and Z but this means that dia/rad is not available. The MSP software is "Mixed Scale Firmware 0.3".
Any assistance would be appreciated.
I bought a new Launchpad, programmed wired to my level shifter and get exactly the same problem the display is totally erratic when the signal inputs are on P2.0 and 2.5 (X)
(01-08-2017, 04:56 PM)edeeec Wrote: I bought a new Launchpad, programmed wired to my level shifter and get exactly the same problem the display is totally erratic when the signal inputs are on P2.0 and 2.5 (X)
This is strange. What kind of scale are you using? Are you connecting the same output to the input?
01-11-2017, 09:41 AM (This post was last modified: 01-11-2017, 10:04 AM by edeeec.)
I am using Chinese Calipers with 1.5v systems. I have one LM339AN with an LM317T supplying the 1.5v. If a caliper is connected to the level shifter it works perfectly on the Z and Y inputs on the Launchpad. However when connected to the X input the display is erratic. I can set 0.0 on Tablet and scale then move read head and the Tablet display jumps to completely different numbers to the scale. The values do not increment perfectly as I move the read head. However if I move the read head back to 0.0 the scale and tablet agree at 0.0. If I connect to Y or Z everything is perfect with either scale on either input. I am powering down the Launchpad between changing inputs. Counts are set at 20480/inch on all inputs and scales and tablet read correctly in mm when on Y and Z. DRO settings - 2.5.10 Build 2016-08-12. Launchpad is Rev 1.5 and I have tried two different Launchpad units.
Thanks for the response
Richard
Not sure if I completely covered your query but
Level shifter his A and B, Scale 1 and 2
If 1 connected to A output to Z ok
If 1 connected to A output to X Erratic
If 1 connected to B output to Z ok
I 1 connected to B output to X erratic
Same with and 2 and Y
Richard
I have taken some readings with my chinese caliper connected as previously discussed and reading the x channel from P2.0 P2.5. The scale and display match perfectly when connected to P2.1 and P2.4.
Scale moved to the left to a stop and zero set. Zero set on the Android Display. Settings in mm CPI set to 20480.
Scale moved to the right and readings taken then moved back to show similar readings on the return.
Scale Display
Reading Reading
0.00 0.00
1.72 38.91
3.01 37.64
4.84 35.78
6.49 34.14
11.16 34.55
18.58 -18.58
21.62 -21.54
26.84 -26.78
38.33 -38.34
52.97 28.46
47.14 -37.00
40.63 -40.64
1.70 38.93
16.56 -15.92
18.61 -18.62
Can it be that the scale is 24 bit but interpreted as 21 bit or Bin6 or some combination of these?
Richard
(01-28-2017, 04:15 PM)edeeec Wrote: I have taken some readings with my chinese caliper connected as previously discussed and reading the x channel from P2.0 P2.5. The scale and display match perfectly when connected to P2.1 and P2.4.
Scale moved to the left to a stop and zero set. Zero set on the Android Display. Settings in mm CPI set to 20480.
Scale moved to the right and readings taken then moved back to show similar readings on the return.
Scale Display
Reading Reading
0.00 0.00
1.72 38.91
3.01 37.64
4.84 35.78
6.49 34.14
11.16 34.55
18.58 -18.58
21.62 -21.54
26.84 -26.78
38.33 -38.34
52.97 28.46
47.14 -37.00
40.63 -40.64
1.70 38.93
16.56 -15.92
18.61 -18.62
Can it be that the scale is 24 bit but interpreted as 21 bit or Bin6 or some combination of these?
Richard
Richard,
It looks like it's misreading a few bits. The weird thing is that the controller clearly understands the protocol when connected to non-X input.
Can you post some pictures of your setup, etc.
Regards
Yuriy
A couple of pics attached, not sure how they will help based upon the problem. Sorry for delay - decorating!
As only two axis a single 339 was used. The top track is 1.5v from the reg. Second track is 5v. The displays are connected through a min din and are wired to the board with the red/green/white/black wires.
Best regards
Richard
(02-23-2017, 08:37 AM)edeeec Wrote: [quote pid='418' dateline='1486308222']
Yuri, Any chance of a comment?
[/quote]
Sorry, missed your post.
Honestly I'm at a bit of a loss. It's definitely a problem somewhere in the controller, not the app itself, but I haven't seen this behavior before.
What happens when you connect the scale to two inputs (or one comparator outputs to two axes)?
Scale connected to one half of 339. Clock and data connected to P2.1 and P2.4. Powered up, connected. Scale and display zeroed. Scale moved, display Y axis and scale value match.
Powered down, P2.1 linked to P2.0 P2.4 linked to P2.5, powered up ,connected.
Y axis display now continually jumping about. If the scale is moved X axis value changes and a number shows without changing most of the time but then for a fraction will show a completely different number..
Powered down.
Just for fun P2.1 linked to P2.5 and P2.4 linked to P2.0. Powered up connected.
X axis jumps about erratically however Y axis now stable and correct and following the scale.
Is the controller trying to supply the clock? I believe you need to do that on some types of scales.
