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USB drive issues
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Some USB drives do not show files when plugged in. We have gotten around this for testing by using USB to SD adapters.

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tutley created this task.Sep 19 2018, 12:47 PM

@marcio found that if you power cycle the machine with the USB drive installed it then shows the files

@tutely: Actually, that is just the theory at this point.

If anyone runs into a problem with a drive not being recognized, please power off your printer with the drive inserted and then power it back on while the drive is still inserted. Then go to the file list once the "Card inserted" message appears. If the files shows up okay, then post here saying so, as this confirms the same behavior we are seeing in R&D.

nickp renamed this task from USB drive issues reading files to USB drive issues.Oct 17 2018, 9:51 AM

@mjpelletier you can use this ticket for the USB update

Steven added a subscriber: Steven.EditedOct 17 2018, 1:23 PM

In the R&D and Marketing joint meeting this was determined we would not provide an SD adapter. If users have to use an SD card for some reason we can preemptively point them to a suggested adapter on Amazon. Also, this ticket is for USB issues. Next time please make a separate ticket for separate topics.

I took a closer look at USB failures and intermittent operation and found that one cause is unstable operation of the crystal oscillator used to drive the SPI to USB chip on the USB Driver Reader board. The crystal oscillator circuit currently uses load capacitors of 20 pF. By replacing the 20 pF capacitors with 15 pF capacitors, I was able to make the oscillator circuit more stable. USB boards that would not start up when the TAZ 7 was powered on began to work with the 15 pF capacitors.

I have ordered a selection of 15 pF, 16 pF and 18 pF load capacitors to test with the USB Reader boards to see which value gives the best stability. Once an optimum value is selected, load capacitors (2 ea.) on the beta build boards will be replaced and the BOM modified for production board orders.

The USB Drive Reader board currently uses and Amphenol USB Type A connector that is rated for 1500 insertions. An Amphenol connector rated at 5000 insertions will be tested on some beta build boards to see if it improves reliability. The new connector has a single unit cost of $0.92 compared to $0.52 for the current connector.

I have found a consistent crash via USB on my machine. It is presently working fine printing from Cura (or at least, has gotten past the point it has crashed via USB.)

At or right around line 12,000 of the attached gcode file, the machine will crash. The machine will just restart at this point. I tested this 3 times from USB - twice from the same USB flash drive, and a third time from an SD card using an adapter. The SD adapter did behave a little differently. Instead of just restarting, it moved the Y axis to the back of the machine, then began moving back to the location it was at, but stopped moving and restarted before the nozzle reached the part again. This behavior was not observed during either USB flash drive print.

I am also including a Cura console log. The crash happens right at the 36,521 instances of "Error:SD read error".

FYI, the gcode file is using ninjaflex in E0, and PLA in E1.

nickp changed the edit policy from "All Users" to "LulzBot Hardware Products (Project)".Oct 25 2018, 11:55 AM
Steven reassigned this task from marcio to mjpelletier.Oct 25 2018, 3:54 PM
Steven added a subscriber: marcio.

@mjpelletier can you post an update here once you've gone through the EMC testing?

After EMC testing and further examination in R&D, I found that the primary cause for the USB failures was from noise generated by the shroud fan. This occurred when the shroud fan was at a setting other than 0% or 100%. The noise was present when the shroud fan was driven in PWM mode. I was able to minimize the noise by placing a 10 uH inductor on the extruder interface board, in series with the shroud fan circuit. I have ordered 22 uH and 33 uH inductors to test and hopefully further reduce the noise.

Almost all circuits using the Maxim MAX3421e USB chip use 18 pF load capacitors on the crystal, I have modified the USB Reader board with 18 pF load capacitors and have seen good results. The boards initialize and have stability when running. I have modified 30 beta build USB Reader boards with the 18 pF capacitors and the addition of a 120 mm ground "pigtail" to help with ESD immunity.

Steven closed this task as Resolved.Nov 16 2018, 2:53 PM

Per my understanding this was largely due to ESD issues we were seeing caused by the Archim design that is now corrected. Closing this for now. If we see more in Alphas, make a new ticket.