Sparkfun Serial Controlled Motor Driver

I just received, and tried this: http://www.sparkfun.com/commerce/product_info.php?products_id=9571

It says “The motor driver can provide up to 4 Amps of current to the motors (2 Amps per motor).” But testing it with a motor that I measured to draw 1A, was way too much for it.

When I try it returns a message to me about overcurrent, but that is ofcurse just when the motor starts. My multimeter can’t measure the peak current the motor draws when it starts, but I suspect it to be around 2A maybe a bit more when it starts.

I then downloaded the source for it, and in it it says it is limited to around 1.5A, and by the look of it, it makes it stop as soon as it is toggled, instead of giving the motor a chance to start before measuring. This I could get around, by editing and putting my own in… But the next problem is that it seems to be very slow… To make one motor work, you send a command, to make the other work you send another command… But to get both working “at the same time” I had to send the commands with almost a second delay between them, which is totally useless for what I want it to do (driving two belts on a tank).

The manual for it says that it will return error messages… And it do, kinda… It tells you when the command is a wrong length, or when it is way too long… Instead of actually returning something useful like “Received ‘notworkingcommand’ syntax is MDS (motor direction speed)”.

So maybe it is like that, or it is broken, or I simply fail to connect the 6 wires to the clearly marked solder points, but bottom line is that I can’t use it and 19.95+shipping out of the window... (shipping from here and back is even more than the 19.95) :-/ And I am now going to order a L298N so I can connect it directly to my seeeduino mega and get the fastest available responses from it…

well that driver “can” handle 4 amps both channels combined at absolute max rating, but for 1 that makes it 2A absolute max, 1.5 to be safe so there ya go

A lovely case of marketing from both parties ::slight_smile:

But it is useless…? Unless you want to control a tiny motor without any load at all.

Thought that the 2A would be something it could handle for x amount of time… not max 1.5A for 5 milliseconds, without giving the motor a chance to start…

Well, if you can update the code on the microcontroller then theoretically you could just take out what’s there and replace it with your own code that doesn’t have long delays. More work for you, of course :slight_smile:

No surprise about the 2A issue…that’s just pure marketing. Without a big heatsink and/or a fan the L298 is limited by heat, not current. In a recent test on an L298-based motor driver product, we found that it goes into thermal shutdown at 1.24A on a single channel (other channel is off) or about 0.8A when both channels are on.


The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, light sensor, potentiometers, pushbuttons

What should I get instead of a L298 then?

I can put the L298 on a heat sink, but the motors will only be on for something like 2 seconds, then off again. I can easily run them with a TIP120, but I want to be able to run them both ways.

You can try a heat sink to start with, though in our tests that only allows the current to increase by a small amount (100mA or so).

If you look at some robot/hobby stores there are lots of motor drivers to choose from in a variety of current ratings. Here’s an L298 product at a shop in Denmark that already seems to have a heatsink attached.

http://www.let-elektronik.dk/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=153&category_id=22&option=com_virtuemart&Itemid=81


The Quick Shield: breakout all 28 pins to quick-connect terminals

Trying that… plus ordered a L298 too so I can try and make my own. :slight_smile:

Can’t wait to test it… That is all I need to get my wifi tank driving around :slight_smile:

Is this for a university robotics competition by any chance?

No, it is just for driving around inside my own house. Controlled over wifi…

The board from sparkfun as an L298 H bridge, what is the diference from using that or a standalone L298? ::slight_smile:

well its got a serial doo hicky attached on it, not that its really that hard to control a hbridge and the op already has it and paid for it …

otherwise I would use the L289 in the though hole package and screw a heat sink to it, but that adds weight and maybe balance problems for a remote rover platform

I dunno, it may not be that big of an issue after startup to even go that far, its just getting that inital kick that seems to be the issue

If the op read the coments at sparkfun in that product page he would see that the Isense pins of the L298 are connected to the ADC pins of the atmega328p and those act as software protections when the corrent is over 1.5A, there is a new software and you can change the adc treshold so the H bridge is disconnected by the atmega and you can have you 4A.

you can have you 4A.

well if you had read this thread there is no way to get 4 amps out of a channel, it peaks max at 3 for under 100us with thermal management which is going to be next to impossible on a flat pack smd

No surprise about the 2A issue…that’s just pure marketing. Without a big heatsink and/or a fan the L298 is limited by heat, not current. In a recent test on an L298-based motor driver product, we found that it goes into thermal shutdown at 1.24A on a single channel (other channel is off) or about 0.8A when both channels are on.

although it may just be enough to fit the op’s requirement

on a side note I hate that people have to go hunt down information on their site, this time it was in the comments, when I got my pic32 I ended up searching though 14 pages of forums to find out I needed to download a modified program uploader to get the durn thing to work

I would never in my life buy anything without first reading all the coments about the thing that I want, because as usual there is always little fails in every product…
At least the datasheet says something about 4A or maybe I saw a different H bridge, sorry :-[

http://www.let-elektronik.dk/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=153&category_id=22&option=com_virtuemart&Itemid=81&vmcchk=1&Itemid=81

Arrived today :slight_smile: And it is doing exactly what I suspected the one from sparkfun would do too, but didn’t.

And here it is, with both pwm pins set to 80 out of 255 :slight_smile:

Speed 120

And a massive cleanup in the code gave a dramatic result…

It is now super agile! MUCH faster responding, and can take a whole bunch of commands without any problems.