Increased step rate for 3 over 2?

3DPMicro

Can I expect a faster step rate with a Duet 3 over a 2? If so any guesses as to how much. I think the D2 ethernets I've been using may be limited with my new build

deckingman

@3DPMicro Depends on the board and to some extent the number of motors being driven, so yes/no/maybe tick as appropriate.

https://forum.duet3d.com/topic/18694/duet-maximum-achievable-step-rates?_=1614633549791

The post by @dc42 on 22nd Feb maybe sums it up, quote

The SAME51 processor on the EXP3HC, SAME54 used on Duet 3 Mini and SAM4E used on Duet WiFi/Ethernet are all 120MHz ARM Cortex M4F processors. So it's expected that the maximum step rates should be similar. The SAME51 and SAME54 have more cache memory so they might be a little faster.

Phaedrux

Also worth noting that in that reply from DC42 he isn't talking about the Duet 3 mainboard, which runs at 300Mhz, and would have a higher step rate accordingly.

dc42

@3DPMicro said in Increased step rate for 3 over 2?:

Can I expect a faster step rate with a Duet 3 over a 2? If so any guesses as to how much. I think the D2 ethernets I've been using may be limited with my new build

The measured maximum step rates for some board/firmware combinations are recorded at https://docs.google.com/spreadsheets/d/1AWA1wLbOaYzxzdQa5LRZvn9rgEk2BuluHy6-_OnD6FY.

3DPMicro

Sorry guys that I wasn't specific. I meant Duet 2 Ethernet/Wifi to 3 MB6HC. Looks like it has significantly more potential according to the data so far.
David,
Can you briefly summarize what "calculation time " ( In addition to the obvious) means and how that effects motion?

dc42

@3DPMicro said in Increased step rate for 3 over 2?:

Can you briefly summarize what "calculation time " ( In addition to the obvious) means and how that effects motion?

If you mean "32-bit square root calculation time" and the other calculations times in that spreadsheet, then it means what it says. Square root calculations are needed when calculating step times during acceleration and deceleration segments, and all the time on delta printers. Sine/cosine and/or other trig calculations are needed when processing G2/G3 moves, and all the time on SCARA and Polar printers. So I keep an eye on the time taken to do these calculations.

3DPMicro

Thank you Sir