Accelerometer Usage

dc42

Interestingly, every single one of these peaks falls on an even 20 sample interval (#20, #40, #60, #80, #100, #120, etc).

I suspect it may be an undetected data overrun then. RRF tries to read 20 values at a time. The FIFO in the accelerometer is 32 values long, so this allows some leeway. Try capturing all three axes and see if it is the same on all of them.

CCS86

@dc42 said in Accelerometer Usage:

@ccs86 said in Accelerometer Usage:

Interestingly, every single one of these peaks falls on an even 20 sample interval (#20, #40, #60, #80, #100, #120, etc).

I suspect it may be an undetected data overrun then. RRF tries to read 20 values at a time. The FIFO in the accelerometer is 32 values long, so this allows some leeway. Try capturing all three axes and see if it is the same on all of them.

I can confirm that X and Y also have these 20-sample peaks.

dc42

@ccs86 what M955 and M956 parameters are you using? I will try the same parameters.

CCS86

@dc42 said in Accelerometer Usage:

@ccs86 what M955 and M956 parameters are you using? I will try the same parameters.

M955 P0 C"twck0+twd0"

G1 X25 G4 S2 G1 X125 F20000 M400 M956 X P0 S1000 A0

ajdtreyd

@ccs86

If you need to buy one, I can recommend the PNY EliteX U3 V30 64GB. It's getting 3.8-4Mb/s write speed in my Duet 2 Wifi.

dc42

@ccs86 I've run the accelerometer on my Maestro and the result is fairly clean:

However, there are some small glitches on the Z reading and it looks like they may be at multiples of 20 samples. I'll try reading one less sample from the FIFO.

dc42

Reading one less sample doesn't help. I can only assume that communicating with the accelerometer creates an electrical disturbance that slightly affects the reading.

CCS86

@dc42 said in Accelerometer Usage:

Reading one less sample doesn't help. I can only assume that communicating with the accelerometer creates an electrical disturbance that slightly affects the reading.

If you read only 10 samples at a time, do the peaks appear at that new interval?

dc42

@ccs86 said in Accelerometer Usage:

@dc42 said in Accelerometer Usage:

Reading one less sample doesn't help. I can only assume that communicating with the accelerometer creates an electrical disturbance that slightly affects the reading.

If you read only 10 samples at a time, do the peaks appear at that new interval?

I didn't try that. I did find that the LIS3DSH has smaller peaks are multiples of 20 samples than the LIS3DH.

tecno

@dc42

Is this one up to the task?

dc42

@tecno yes, that's the LIS3DSH board that I tested with.

tecno

@dc42

Thanks !

Sotidii

G1 X-20 G4 S2 M956 P121.0 S1000 A0 G4 P10 G1 X50 F20000

Error: M956: Accelerometer is already collecting data

gives an error message

Duet 3 3.4.0-b2
DSF
Tool Board 1.1

dc42

@sotidii please send M115 B# where # is the CAN address of the tool board, to verify the tool board firmware version. There was a bug with similar symptoms in unofficial beta builds of the tool board, but it was fixed in the official beta release.

Sotidii

@dc42
M115 B 121
FIRMWARE_NAME: RepRapFirmware for Duet 3 MB6HC FIRMWARE_VERSION: 3.4.0beta2 ELECTRONICS: Duet 3 MB6HC v0.6 or 1.0 FIRMWARE_DATE: 2021-08-03 12:42:44

dc42

@sotidii said in Accelerometer Usage:

@dc42
M115 B 121
FIRMWARE_NAME: RepRapFirmware for Duet 3 MB6HC FIRMWARE_VERSION: 3.4.0beta2 ELECTRONICS: Duet 3 MB6HC v0.6 or 1.0 FIRMWARE_DATE: 2021-08-03 12:42:44

Run the command again, but don't put a space between the B and the 121.

Sotidii

@dc42
M115 B121
Duet TOOL1LC firmware version 3.3RC3 (2021-05-26 12:30:20)

dc42

@sotidii said in Accelerometer Usage:

Duet TOOL1LC firmware version 3.3RC3 (2021-05-26 12:30:20)

Please upgrade the tool board firmware to version 3.4beta2.

Sotidii

@dc42 OK!

CCS86

@dc42 said in Accelerometer Usage:

@ccs86 said in Accelerometer Usage:

@dc42 said in Accelerometer Usage:

Reading one less sample doesn't help. I can only assume that communicating with the accelerometer creates an electrical disturbance that slightly affects the reading.

If you read only 10 samples at a time, do the peaks appear at that new interval?

I didn't try that. I did find that the LIS3DSH has smaller peaks are multiples of 20 samples than the LIS3DH.

Is eliminating these false peaks something you plan on pursuing? It seems like they have the ability to skew the analysis.

I tried manually removing the peak samples from a copy of one of my logs, for the purpose of comparing the analyzed result. But while the modified log is displayed correctly in DWC, the analysis always shows a blank chart.