Unfortunately, each half of the bridge can only handle up to 600mA, which is relatively low, but it’ll sufficient for controlling the basic motors I plan on using on the prototype robot. By driving PWM signals to the control inputs of the chip, the speed of the motors can also be controlled. As shown in Figure 10 of the datasheet, each half of the chip can function as a bidirectional motor controller. I’m using an L293D chip for the motor driver. My planned use for this prototype will be to control the main drive motors of the robot base module. It’s fairly simple excluding the Arduino that handles communication and control it only consists of encoder connectors and a dual H-bridge. The first board I’ll go over is the Motor Board prototype. I also decided to use an adjustable voltage regulator so that the output voltage of the regulator could be set higher than 5V so that the actual voltage seen after the diodes would be 5V after the diode forward voltage. I was worried that the regulator wouldn’t be able to supply enough current to the motors and so I added the diodes so that multiple power boards could be safely put in parallel. Each regulator is limited to roughly three amps of current with the multiple boards, Arduinos, and the Pi Zero taking up a fair chunk of that.
My reasoning behind this was to provide the ability to use multiple power boards, and therefore multiple LiPo batteries, in the system. I also added four beefy diodes between the regulator and the 5V supply for the system. The charging circuit is fairly straightforward so I’ll just explain the step-up circuit which takes the output voltage from the single cell battery, passes it to the four pin input side of the step-up regulator, and gets back a boosted voltage from the second four pin output side of the regulator. It’s two components are a single-cell, LiPo charging circuit based on the MCP73831 and the Pololu adjustable step-up regulator.
The design for the board to supply power to both the Pi Zero and robot modules is fairly simple.
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