I've been going through the picaxe 28 manuals and the part about motor controllers is a little confusing.
When is it appropriate to use the Lxxx motor driver chip and when should one use the darlington chip?
My understanding is pwm technique is when we have neither of the above chips?
I'm using the Tamiya twin motor http://www.pololu.com/catalog/product/61 some of you have used. For this motor, do I need one power source or two? And darlington or will Lxxx motor driver suffice?
You should only use the motor-driver for the motors - no darlington.
It is optional weather you want to use one or two power-sources, the “Lxxx” can do both.
It is my personal experience that it can be hard to draw enough power out of the Tamiya twin motor - so I’d use only 2 cells for the logic, and 4 for the motors.
Is the Lxxxx chip pin Is the Lxxxx chip pin compatible with how the darlington chip is setup with the Picaxe? I think the 28 board has a dedicated DIP socket for the motor driver chip.
This is correct, but the L293D has power, ground and output on both sides of the chip too. The socket for the darlington chip probably doesn’t match the same power/ground pins as the motor driver.
I’m pretty sure the 28x board has 3 DIP sockets: 1 for the Picaxe, 1 for the darlington and 1 for the motor driver.
In Frits’s “First Robot” tutorial, you’ll notice that he uses the bottom socket (depending on which side of the board you thing is top) for the motor driver: https://www.robotshop.com/letsmakerobots/node/17
The cool thing about this dedicated socket is that it’s pre-wired for the L293D chip to the 4 - 7 output pins and the board has an “A” and “B” area where you can solder your motor leads to.
To be honest, I haven’t played with the 28x board yet, so this is all from what little I know about it. I’ve been working with the 18x board, and had to make a custom pin harness to adapt the L293D chip to the darlington sockets, since that board doesn’t have a motor driver socket.
