Web Site: www.parallax.com Office: (916) 624-8333 Forums: forums.parallax.com Fax: (916) 624-8003 Sales: sales parallax.com Sales: (888) 512-1024 Technical: support parallax.com Tech Support: (888) 997-8267 HB-25 Motor Controller ( 29144) General Description The HB-25 motor controller combines the power of an H-bridge with the simplicity of a servo. The HB-25 is more than just a motor driver chip connected to some logic and high current on a PCB. A quality H- bridge involves an efficient thermal design, which is what the HB-25 has accomplished through a machined heat sink and fan to draw air over the H-bridge. Additionally, it uses a thermal bonding agent to transfer heat from the motor driver chip to the heat sink. The result is a high-current motor controller with great thermal characteristics and requiring no additional hardware for cooling. Before using your HB-25 Motor Controller, read and understand this entire document, including the Precautions section beginning on page 4. Features 25 A continuous current, 35 A surge 13.8 VDC Works with any size motor up to HP Control a DC motor just like a continuous rotation servo A single pulse required to set motor speed Compatible with all Parallax microcontrollers 2 operation modes: control 1 or 2 HB-25s independently from a single I/O line Built-in automatic shut-off if invalid pulse widths are received Communication Timeout mode option for automatic shutoff Application Ideas Robotics Automotive Applications Resources and Downloads Check out the HB-25 Motor Controller product page for the example source code and other resources: Modes of Operation The HB-25 connects to the microcontroller much like a servo. You can use an extension cable (such as Parallax part 805-00012) or a custom cable to connect the HB-25 to your controller. Reversing the M1 and M2 connections to the motor effectively reverses the direction. The HB-25 has two modes of operation which are selected by the jumper labeled J. Mode 1 is Single Mode, where only one HB-25 is present on the microcontroller I/O line. In this mode, the HB-25 can be controlled with as little as a single pulse from your microcontroller. Mode 2 is dual-mode, which is used when connecting a second HB-25 to a first HB-25, rather than connecting directly to the microcontroller. This powerful feature allows two HB-25s to be independently controlled through the same I/O line, saving I/O pins. Two HB-25s are required to use Mode 2. Mode 1 Mode 1 is selected when the jumper labeled J is in place. Figure 1: Single Mode Selection Mode 1 Communication In this mode, a single pulse value sent to the HB-25 can control the HB-25 no refreshing is necessary, as is the case with a servo. For compatibility however, you may send the HB-25 pulses every 20 ms just like a servo and it will function the same. There is a hold-off time of 5 ms where the HB-25 will ignore incoming pulses. As a result, the unit should not be refreshed more frequently than about 5.25 ms + pulse time. Pulse time can be anywhere from 0.8 ms to 2.2 ms. If the HB-25 receives a pulse outside of this range, it will temporarily shut off the motor until it receives a valid pulse. Figure 2: Single Mode Communication The maximum time between pulses is unlimited, since a single pulse is all that is required to set the unit running indefinitely. This is especially nice for BASIC Stamp users with complex sensor code which may not have had sufficient time to refresh servos during the main loop. You only need to send a new pulse when you are ready to change the speed of the motor (or stop it). Parallax, Inc. HB-25 Motor Controller ( 29144) v1.2 4/07 Page 2 of 8