issue with baud rate for gen6

I have been using a baud rate of 38400 since i first got the gen6, and it's been working fine, but i've seen many posts about how anything above the default, 19200, is unnecessary. So, i went and put it at 19200 in the configuration.h file and went about printing.

But i've noticed that since i made that change, the machine pauses, sometimes for 4-5 seconds, then starts up again. pausing leads to ooze and blobs, so my print quality has gone down.

I've just now switched the baud rate back up to 38400 and it's printing much better, with no pauses.

the gen6 uses the AT mega 644p.

Which firmware (and revision of that firmware) are you using?

Some firmwares will pause every time, as they do no buffering. The amount of time such a firmware will pause is dependent solely on baud rate. Others do an fair job of buffering, though they still have problems with serial communications while printing. Others still are quite good at multi-tasking, and have large buffers to boot.

So it's not *just* rate, it's also buffering, and how much calculation is pre-done before each moves starts.

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I'm building it with Baling Wire

I'm using plain old fiveD. actually it's mendel-parts firmware, but it only has a couple lines here and there for gen6 stuff.

What other firmwares should i try? i'm tempted by 5d on arduino, since there seems to be more development there, but i don't really follow firmware dev that much.

I have no idea. I'm working on fiveD_on_arduino stuff, mostly because the only chip I've been able to get to work is a 168. I'm not really following the development of any other firmwares.

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I'm building it with Baling Wire

i'll add this tidbit to the gen6 wiki page. mendel-parts uses the default of 19200 in their firmware, so i assume this is happening to others (or maybe it's just me). Other people might not even know this is a problem if they never played with the baud rate.

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i've seen many posts about how anything above the default, 19200, is unnecessary.

That's true, if you have less than about two lines of G-Code per second, but there's also no gain in using lower baud rates. The ATmega collects the incoming signal independently from the main processor and always passes the data one byte at a time to the main loop, so the work load is always the same.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

What sometimes happens is that the firmware receive non-usable info in its buffer. Info like: extruder on, or extruder off. This is stored in the command buffer and whenever this buffer is emptied faster than it is filled, you'll get some pauses.

This is due to the data transfer, the used g-code processor and the intelligence of the used host software.

A higher baudrate makes that you don`t experience these problems.

Well actually i also had a related trouble with my machine, when i was using 19200 the coms crashed at random when trying to print but once i changed the firmware to 38400 the problem never came back

This problem didnt seem system related as i experienced same in windows and linux difference being windows worked sometimes but linux never worked

Now it flawless on both

Did you have to change your USB's speed as well as the Firmware and Repsnapper (or whatever your host is) baud rate? I'm having the same problem at 19200 and I haven't found a good connection at a higher rate. I have, however lowered it to 9600 because my USB speed is set at that and if I try to change that to match a high baud rate it doesn't connect. -Win7, repsnapper, Gen6, SF40