Mark's Antweight build

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MarkR
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Re: Mark's Antweight build

Post by MarkR »

Oh cock.

It was all going swimmingly (see above picture).

But now my Dasmikro seems to have blown up, during a test this evening one channel got locked on full power, and the smoke came out.

I will need to totally disassemble it to see if it's a gonner (probably yes) - it does not smell nice.

Looks like I may be evaluating H-bridge boards after all.
Robots: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?
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MarkR
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Re: Mark's Antweight build

Post by MarkR »

Paul, thanks for the suggestion:
Paulmchurd wrote: Thu Mar 22, 2018 11:43 am I found another nice looking h-bridge. The dasmikro seems to have been taken off banggood.

https://m.ebay.co.uk/itm/Stepper-Dual-M ... =547517332
After the untimely demise of the Dasmikro, I bought this dual H-bridge board. It's about the same size as the Dasmikro, but easier to wire because there are actually holes in the board, unfortunately there are a lot more control lines needed (6 vs 2)

I needed to add a hacky voltage regulator on (nasty soldering, heat-shrinking) because the TB6612FNG does not have a regulator.

It seems to run nicely. But weird. I can control the speed in software from the Raspberry Pi and apply the brakes too. I wrote a blog post about it: https://marksverbiage.blogspot.co.uk/20 ... 12fng.html
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Shakey
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Re: Mark's Antweight build

Post by Shakey »

The TB6612FNG used to be a mainstay in ants before the Nano ESC's took over. Good chips and pretty robust. A bit long in the tooth as far as driver chips go nowadays but still work nicely.
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Paulmchurd
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Re: Mark's Antweight build

Post by Paulmchurd »

Shakey wrote: Tue Apr 24, 2018 5:16 pm The TB6612FNG used to be a mainstay in ants before the Nano ESC's took over. Good chips and pretty robust. A bit long in the tooth as far as driver chips go nowadays but still work nicely.
What moter driver chip would you recommend instead? I've been searching around and found a few but I really have no expiernce testing them.

L298n (if that's the right code) seems popular for Arduino.

Unless you build your own esc . With individual chips on a pcb. You probably won't get below 4 wires.


There are a fair few other h-bridge that use less pins but I don't know if they are 3.3v or 5v. Search on alixpress. Super cheap as well.
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MarkR
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Re: Mark's Antweight build

Post by MarkR »

I think that L298n is even older.

The TB6612FNG datasheet is from 2007. The chip itself seems a bit whacky the way it's configured, but it operates ok. Maybe there are more modern, better ones, possibly in a nicer package. To solder, the fine pitch SMD part does seem like it could be tricky (I didn't solder it, it came on a breakout board without headers, which is ideal)
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Re: Mark's Antweight build

Post by Paulmchurd »

Yea, I don't fancy soldering these tiny chips. The das Mikro was tricky enough.

I've found this list of motor controller chips. Might be able to help search for a breakout board / have a go at making your own Esc.

https://uk.rs-online.com/mobile/c/semic ... -ics/?pn=2
Deathly Hallows
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Re: Mark's Antweight build

Post by Deathly Hallows »

I was also looking at the DasMikro but the quality looks questionable looking at the photos on eBay and banggood. I found this TB6612FNG with headers on eBay - https://www.ebay.co.uk/itm/Motor-Driver ... 2502977076 which I am going to try. Soldering onto leads will be a lot easier. Just need to hold the leads in place.
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Re: Mark's Antweight build

Post by peterwaller »

You probably realize this already but just in case you don't the TB6612 is just a motor driver chip and is not capable of working with the signals from the receiver but needs a micro controller to convert them. The DasMikro is a complete motor controller board and can work directly from a receiver.
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Re: Mark's Antweight build

Post by MarkR »

peterwaller wrote: Tue May 01, 2018 8:30 am You probably realize this already but just in case you don't the TB6612 is just a motor driver chip and is not capable of working with the signals from the receiver but needs a micro controller to convert them. The DasMikro is a complete motor controller board and can work directly from a receiver.
Paul is absolutely right - the H-bridge is not a replacement for a ESC.

The ESCs take "servo pulses" and drive motors through an H-Bridge (i.e. in both directions) with PWM for speed control.

The H-bridge does none of this, it just takes digital signals (this chip is ok with 3.3V logic) and drives a motor clockwise, or anticlockwise.

Unless your RX module can be programmed to output the correct signals for the H-bridge, it won't work with a standard RX. Normal RX output servo pulses (for e.g. servos!)

The reason I was able to use the TB chip was that I'm using a microcontroller anyway, and I was just programmatically sending servo pulses to the Dasmikro (before it failed). I've now modified the software to send different types of pulses.

It also needs more signals; the TB H-Bridge needs (approximately) 3 signals per channel, but the ESC only needs 1 signal per channel. That might be a problem for very tiny microcontrollers if they don't have enough output pins; it isn't a problem for the Raspberry Pi as it has enough.

My design now uses two Dual H-bridges and one external voltage regulator - to allow the Pi to drive the weapon motor (flipper, 1xN20 gear motor) and the drive (4x N20 gear motor). Quite surprisingly, it actually works!
Last edited by MarkR on Tue May 01, 2018 9:38 am, edited 1 time in total.
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Re: Mark's Antweight build

Post by Paulmchurd »

Sorry to bounce your build diary all over the place. I found this chip last night that I thought people might find useful.

It's a micro controller the size of a 5p piece. With 9PWM outputs. I've ordered one and will post in my build about it. It's also a British product!!!

Hook this up with a h-bridge and Rx. It's tiny and light weight.

https://nerdonic.com/products/exen/mini
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