Non HE280 accelerometer upgrade

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greyghost
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Non HE280 accelerometer upgrade

Post by greyghost » Mon Apr 17, 2017 10:50 am

So I didn't feel too keen to buy the HE280, cabling and rewire my v2. I looked at the wiring diagram and config.h code and figured that any accelerometer that communicated with SDA and SCL would work.
So I picked up this one on amazon. UCTRONICS MPU-6500 6-Axis Sensor Module Gyroscope Accelerometer https://www.amazon.com/gp/product/B01DIPU152/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
From the wiring diagram http://seemecnc.dozuki.com/Document/31/.pdf and https://cdn.shopify.com/s/files/1/0276/2543/products/71210_1024x1024.jpg?v=1473171987
on the I2C the red wire goes to SDA and black wire goes to SCL. I have a rambo 1.3L board so I'm not sure how much different that is from the board the v3 is using but they look similar.

Anyways I ran my wires and hooked it up and booted up my terminal in matter control and when I turn the printer on I get stuck on a loop with this message:
<-start
<- Free Ram 869
<- X:0.00 Y:0.00 Z:0.00 E:0.00
<- Autoretract: 0
<-SpeedMultiply:100
<- iis2dh accelerometer initializing...

It just loops after that. From looking at the code it isn't getting a reading response from the accelerometer so it isn't initializing. I've seen people have similar issues with the HE280 and the suggestions were the wiring. I've checked that don't believe that the be the issue. I even used my breadboard wires and hooked it right into the board and get the same issue.

I was reading on this post http://forum.seemecnc.com/viewtopic.php?t=10876 Which is where I got the wiring diagrams and it was wondering if I need to connect the INT Probe wire as well. Does anything use that on the v2 board right now?

Is there a way to trouble shoot if the accelerometer is working without matterhackers?
I have a raspberry pi and breadboard so I can trouble shoot the accelerometer if I need too but I'm not sure how I'd do that. I attached a photo for the accelerometer and board and my configuration.h If anyone has any ideas on how or if I can get this working let me know.
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pouncingiguana
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Re: Non HE280 accelerometer upgrade

Post by pouncingiguana » Tue Apr 18, 2017 8:24 am

The problem is that the firmware is programmed specifically to work with the HE280 accelerometer board. It has it's own set of commands it fires off to initialize, set sensitivity, etc. It's also worth noting that when probing, the HE280 signals a bed hit over another wire (blue wire going to PS ON on the Rambo), not over the I2C connection. It's possible to get another accelerometer to work, but you'll need to crack open the firmware and recode the functions that do the talking. Grep for "void accelerometer_" and you'll find them.

It would be a lot easier just to use the HE280 board, even if you keep the stock hot end. All you'd have to do is find a way to mount the board and run the extra PS ON wire back to the Rambo and you're good to go. Either path is possible, just depends on where you want to spend your time.

Dale Eason
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Re: Non HE280 accelerometer upgrade

Post by Dale Eason » Wed Apr 19, 2017 6:04 pm

The way the rambo firmware uses the accelerometer is not the way you expected. What it does is use the i2c interface to setup the accleerometer to set the INT line when the acceleration exceeds some threshold. Then it monitors that line only during special moves during the calibration process. When that line changes state the software then believes the acceleration has exceed the threshold as it would if it was stopped by the plate. So you will need to use that line. The V2 upgrade stole a line from the PS-ON and reconnected it to the INT on the HE280 board. Then It rerouted it I think to a different spot on the Rambo that would read the INT line.

So you need to research how that all was connected. Then do something similar as well as maybe change the initialization code to what your board needs.

Dale Eason

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greyghost
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Re: Non HE280 accelerometer upgrade

Post by greyghost » Sat Apr 22, 2017 7:52 pm

That makes sense. I don't have a problem coding it, but my preference is to use as much stock as possible. This one was like $5.00 so I figured I'd give it a try. Thanks for the clarification.

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