Ok so I’ve been searching and searching all day for a H-Bridge that can supply the higher current for the dual output motors I am hoping to use. I think I found one and just want to get some educated input on it.
This is the only other one I have found that even looks like it might work.
Are you planning to swap out the existing (same foot print) H-Bridges or are you going to make a new pcb?
There has been some discussion on this in the github for electronics.
Well I had resigned myself to using a breadboard and wires to make the connections to the stock PCB, But then I started diving deeper into the schematics and found that we aren’t using the stock H-Bridge in the same output configuration as the Manufacture’s output configuration. As you can see in this side by side comparison.
So now I’m waiting for more qualified input. If we can/are tailor configuring the H-Bridges then this got a whole lot easier. Maybe:crossed_fingers:
I found about five other H-Bridges with the same footprint and higher current capabilities. I just kept rejecting them due to the pin configurations not matching. Even the same manufacture’s output configs are vastly different for different chips in the same family. Meaning same chip (PowerSO20) different current capabilities vastly different configs.
Actually, they are using it correctly, they just chose not to do any current sensing. Typically you’d want diodes on the power rails to prevent the windings of the motors from creating spikes but it’s not a “got to have”. I did a quick search on the H bridges you posted and it doesn’t look like the pin out will work out with out haywiring and clipping some of the N.C from the pads. If money isn’t a huge issue I’d look for a COTS (Current off the Shelf) solution to keep things from being messy. You said you found 5 other h-bridge IC’s try looking for a breakout board/eval board for them. That way it’s just plug and play.
It was the GitHub schematic that was throwing me off, and making me think the chips had been reconfigured. It was simplified for ease of reading.
He’s the Stock and Higher Curent chips side by side with moddified connections to make it work. If anyone sees a mistake please speak up.
The eval board is another $40 each if you order at least 16.
There is some issues with this setup. One, Vboot and VCP have to be biased correctly as in the typical application on page 12 of the datasheet. Furthermore according to the datasheet it can only drive 2.8A which is not really gaining you anything from the 2A of the L298. I did however find something that might get you going, a board that gives you 7A per channel and is pretty cheap (In my eyes). Here is the link:
Never used it so don’t hunt me down if issues arise. All you’ll have to do is supply voltage and the correct signals to the board and you are good to go.
If I went with a whole board would I be replacing the stock board or wiring two boards into the stock board. Where the stock is the interface between Mega and the two driver boards? I found tons of seperate boards in my searching. Just wasn’t sure how I was going to get them to connect to the motors and encoders. Figured I’d have to build a third board to bridge the stock and H-Bridge.
I also found a military grade 30amp chip. That for the life of me I can’t remember where I found it at right now. Though that likely would fry motors
Hey that’s life right. Can’t learn without making mistakes.
The hunt continues. I’ll get back on this tomorrow, best to step away for a few hours.
Thank you for your input. Very Appreciated.
That I’m not entirely sure, I don’t even have a Maslow yet lol…I’m waiting patiently for the September shipment. Taking a look at the pictures of the shield it looks the the 3 white connectors are for the motors. The motors probably have the encoders inside them and provide feedback that pass through the sheild to the mega. Im to lazy to look up the schematics so you’ll have to double check. If this is correct you have two options. One, desolder the L298 chips and solder jumpers from the IN,OUT,Enable on the shield and connect them to the board. This is risky because if you mess up you run the risk of destroying the shield. Another option is to buy the encoder/motor connector and take off the shield and jumper directly to the new h bridge board and arduino assuming you know the pins to jump to (in the schematic i’m to lazy to look up). You’ll have a bunch of jumpers but some tiewraps will go along way. A costly option would be to design a new shield with the new h-bridges on them and motor connectors.
I think the 30 amp chip is way overkill, but your motors will be fine. They draw the current they need.
This is the Very 1st IC I found, but gave up on it when the pin config was different. It says 6a continuos and 7a peak, but I can’t for the life of me find if that’s per channel or combined. Then there’s the fact that completely different terminologies are used on the output config diagram.
PDF Data sheet
They also have a progamable 1.5a to 8.6a version
Infineon TLE8209-2SA 1.5a TO 8.6a
TLE8209-2SA data sheet
I guess I lied, cuz I didn’t stop looking today.
Doesn’t matter it needs serial data input words so unless you want to mess with the firmware i’d give up that dream.
Actually, the SPI serial interface on that chip is mostly for reading diagnostic info. The current Maslow uses some of the SPI pins for a different purpose, so that won’t be available.
The control signals for this chip are much like the h-bridge chip in the Maslow - DIR for motor direction and PWM for speed. Unlike the one in the Maslow, this chip only drives one motor. That might be in aid of handling the higher current. One would need to find room for three of these with their heat sinks, capacitors, etc., and make the appropriate wire connections, but I think the firmware wouldn’t need major changes to use them.
Thanks for clarifying Blurfl, thats what I get for not reading the datasheet before talking. I still think finding a COTS board is the way to go and just jumping the signals IN,OUT,EN to the board to keep the current Shield and motor connectors . Save time and heartache
It sure would save time. Have you seen such a beast?
@cypherror I’m willing to do what ever it takes. The connecting all the components part not a problem at all.
I understand how coding works, but it’s a foreign language to me.
@blurfl I have, but I discounted them, due to I was looking for an IC. I also discounted them, because I couldn’t see how the encoder was going to interface with them.
I saw a stackable one that plugs directly into the MEGA, and they daisy chain.
Those use a different approach to motor control from the Maslow, and each board could only control one motor bidirectionally.
They offer this board that uses the same control signals as the Maslow, though from different gpio pins, so it’s not a ‘plug-in’ solution. One would need to build some ‘Frankenstein cables’ to connect this board between the motors and the Mega.
It uses the L8858 motor control chip which includes SPI diagnostics and control of some of the characteristics, but the present Maslow design makes that unavailable. They claim 6A continuous current on all four motors, and that without heat sinks. The chip has sophisticated protection built in.
That’s definitely one of the first boards I looked at. Making cables wouldn’t be a problem.
I thank you for ALL your help.
Would this board work Robot Driver board It’s a little cheaper each channel is rated for 4.5amps Which fits perfectly with those double post motors. I’d be able to save around $17.
In the link I posted above.