![]() ![]() The idea was: 6xAA provide 1.5A, a 9V block provide 700mA, so both put in parallel should provide 2.2A. Because the batteries are a limiting factor I added another 9V block. I don’t know where the difference of 200mA comes from, but it doesn’t really matter for any further working with the motors.Ĥ. The 6xAA can provide about 1.5A, which is even less than 1.7A. In this case not the limit of the DRV8833 is hit, but the limit of the batteries. The next value is 1.7A when both motors are stalled. This is near to 1.5A – so this makes sense.ģ. Because of that the calculation must be 1.2A + 200mA = 1.4A. That’s because the DRV8833 is limited to 1.2A per channel. So the total current should have been 2A + 200mA = 2.2A, but the current is only 1.5A. As stated in my previous post one dc motor draws 2A if it’s stalled. If one motor is stalled, the current goes up to 1.5A. (Details about the provided Makeblock motors can be found here)Ģ. This is a bit more than expected, because the dc motors should only draw 200mA per motor. As you can see the current with no torque applied is about 600mA. ![]() The measurement was taken at the battieries, so the multimeter shows the current of both motors in total.ġ. Both motors with no torque applied, 6xAA batteries Both motors stalled, 6xAA batteries and 1 9V block in parallelġ.One motor stalled and one motor with no torque applied, 6xAA batteries.Both motors with no torque applied, 6xAA batteries.What I was interested in most was the actual current provided. It’s just giving the maximum power to every combination of the two motors, like both forwards, both backwards, one forwards – one backwards and the other way round. ![]() The code itself is really straight forward. So the value with 100% correct cabling with nearly no resistence should have been 2/3*256 ~ 171 in Arduino pwm. I think this is a bit related to the usual resistance of cables and contacts, but in addition is due to my moderate soldering skills ). This simply didn’t work because there’s a voltage drop in my cabling. I thought: my batteries provide 9V, my motors can cope with 6V, so just use 2/3 * 9V = 6V. As of my calculations the value should have been something like 2/3 * 256. The problem was finding the right pwm value. ![]() You can look it up in the spec-sheet additionally.Īfter cabling was done, I had to adjust the pwm to correctly control the motor. But as stated before I don’t need the full current of the dc motors because my project is not about driving fast but simply drive, so the DRV8833 should be sufficient.Īs usually I wanted to do a Fritzing diagram, but there’s no part for the DRV8833 available, but I found a diagram at the Pololu website which shows the cabling. You see that this is less than 2×1.6A=3.2A which I mentioned in my previos post about the L293D. Here are the values regarding supported voltage and maximum current: Motor driver:Īs you can see the DRV8833 can cope with a current of 2.4A peak total. So I chose another motor driver which can handle more current – the DRV8833 as a motor driver shield built by Pololu.Īs stated before the new motor driver should provide less voltage drop and higher maximum current. The problem was simply the maximum current the L293D is able to cope with and in addition there’s a high voltage drop at the L293D which isn’t very helpful. Perhaps you read my post about the L293D where I explained why I have to use another motor driver. Today I will describe how to use the DRV8833 motor driver. ![]()
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