Gen6: checksum errors when trying to print
I'm trying to print for the first time. I've compiled libreprap and repsnapper from github, last version, under linux. I can connect to the gen6 board, and issue simple commands under the tab "printer controls" (like moving a few steps in X, Y and Z, turn on and off the heater, etc). Optos are ok. Temps are ok (checked with M105, IIRC). I can even extrude a bit of PLA.
I load an STL file, convert it to gcode, hit "print". At first, things look promising: the printer homes, goes to the starting position for the print, etc. However, it nevers actually starts printing.
The first weird thing is that the "Printing:" progress bar progresses very fast (it finishes in a couple of minutes).
Under the tab "comm" I can see:
(Removed a zillion lines: commands sent TO the printer, and only a few "ok" FROM the printer. Here comes the interesting part:)
N2950 G1 X49.65 Y39.0363 E12676.7 F1000*58
N2951 G1 F1000*112
N2952 G1 Y40.4505 F3828.43*13
N2953 G1 Y41.8647 F1000*45
N2954 G1 F1000*117
N2955 G1 X48.5893 Y42.9254 E12678.2 F4000*52
N2956 G1 X42.9254 Y48.5893 E12686.2 F4000*54
Serial Error: checksum mismatch
N2957 G1 X41.8647 Y49.65 E12687.7 F1000*55
N2958 G1 F1000*121
N2959 G1 X43.279 F3828.43*60
Serial Error: LineNr is not the last lineNr+1
N2960 G1 X44.6932 Y49.65 F1000*115
N2961 G1 F1000*115
Serial Error:Recieved a LineNr code without a Checksum code or Checksum without LineNr
N2962 G1 X45.7538 Y48.5893 E12689.2 F4000*58
(and so on...)
Every run is the same, with minimal variations (somestimes I get "rs 11", sometimes "rs 6").
IMHO, it seems as if repsnapper (or libreprap) is "spamming" the printer, i.e. it's ignoring flow control. Is it "normal" for repsnapper to send about 3000 lines of gcode, without waiting for the "ok"s of the first lines?
The cable seems ok. I've even recompiled and uploaded succesfully the gen6 firmware several times. I've tried setting the baud rate to 19200, 38400... and even 115200! The outcome is the same. Note I can send the firmware thru the cable without errors.
Apart from the baud rate, I have only reversed a couple of axis directions (I'm building a prusa), I've made no other changes to the firmware.
Edit: actually, I did another change, I changed the "resend" response to "rs", to conform to gcode specs, as mentioned in this thread: viewtopic.php?f=35&t=310&view=previous
However, I get the same results with or withour this change.
I've searched the whole internet for hours, to no avail.