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New PCBs

A project log for A million Times 120 clone

Another attempt of clone the beautiful clock-art-installations of Humans Since 1982

CFCF 11/23/2018 at 22:449 Comments

We are still working on the project. The new PCBs are running quite well. So a first prototype might be coming in the next weeks.

We are now fixed with four steppers for each PCB. So each bigger clock should have a horizontal number of individual clocks, which can be divided by four. For the smallest version of 24 clocks it fits perfectly and for any bigger one this shouldn't also be a problem.

Discussions

deanar wrote 12/10/2018 at 17:34 point

How did you find x40 reference point? The same small 1x2 mm magnets with hall effect sensor?

Can you show a picture of setup?

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chaterrony wrote 11/30/2018 at 16:24 point

I follow you now for some months and hope to see your 24 face prototype soon :-) What is the advantage to go with CAN compared to I2C communication? My project is build up with I2C as this was the easiest for me :-) As beginner in this topic, I didn't wanted to try other bus systems. But if there are better alternatives, I would be interested in. My approach is with an ESP32 as master and ATMEGA328 as slaves. Cost not a lot and works well. However, the I2C communication seems not to be 100% reliable, sometimes a handle get a wrong command??? So I would be interested to see the CAN alternative - if there are significant advantages.

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CF wrote 12/04/2018 at 09:09 point

I2C is only made for short distances, like within the same PCB. If you think about a large array of individual clocks the distance between the master and slave PCBs can go up to more than 2 meters. With I2C it's propably only possible by using level shifters and set the signal to 12-15V. This may work, but I2C is still not made for these long lines.

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wuzandfuzz wrote 12/05/2018 at 14:54 point

I agree.  I almost went with rs-485 since it is almost unidirectional, but you basically need a physical layer that is long distance capable.

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wuzandfuzz wrote 11/25/2018 at 16:59 point

I’m working on basically the same project.  I’m also using can to address master boards with a micro driving 4 motors- just finished laying it out. I did elect to make each board seperate for each motor and run cable to each motor via ribbon cable for control. 

 Any reason you chose the stm32? I was going to roll my own Microcontroller board but I found it was cheaper to buy arduino nanos for $1...

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CF wrote 11/25/2018 at 20:04 point

The STM32 as bluepill is also available for less than $2 and it has more memory space and CAN directly implemented. Also there are two SPI and two I2C. So more options for fancy additions...

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CF wrote 11/24/2018 at 07:56 point

I ordered them at PCPWay, but any Chinese producer can do this. They are "only" 405mm wide. The steppers are a little bit noisy. For a clock with more than 100 faces it really could make some noise. So lets see, what the prototype with 24 faces will show to us.

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Jan wrote 11/24/2018 at 08:42 point

Yeah, they all do it. But at their own rates :) That's why I asked... But looking at your BOM, the PCBs sure aren't the most expensive part hehe

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Jan wrote 11/24/2018 at 06:58 point

Wow, those PCBs are huge! Where did you order them? DirtyPCB? 

Anyways, smooth rotation of the steppers, are they noisy? 

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