Schrittmotor Treiber Breakout mit dem Texas Instrument DRV8824, er besitzt einstellbarer Strombegrenzung und sechs verschiedenen Schritt-Betriebsarten. Der Treiber ist für Spannungen von 8-45V geeignet und kann einen Strom von 1,2A per Phase ansteuern.
This product is a carrier board or breakout board for TI’s DRV8824 stepper motor driver; we therefore recommend careful reading of the DRV8824 datasheet (1MB pdf) before using this product. This stepper motor driver lets you control one bipolar stepper motor at up to 1.2 A output current per coil (see the Power Dissipation Considerations section below for more information). Here are some of the driver’s key features:
We also carry a DRV8825 stepper motor driver carrier that can serve as a direct, higher-power substitute for the DRV8824 carrier. The DRV8825 can deliver up to 1.5 A per coil without a heat sink (2.2 A max with sufficient additional cooling). The only way to tell our DRV8824 carrier apart from the DRV8825 carrier is by the markings on the driver IC; if you have a mix of the two, you might consider marking them (there is a blank square on the bottom silkscreen you can use for this).
This product ships with all surface-mount components—including the DRV8824 driver IC—installed as shown in the product picture.
Some unipolar stepper motors (e.g. those with six or eight leads) can be controlled by this driver as bipolar stepper motors. For more information, please see the frequently asked questions. Unipolar motors with five leads be used with this driver.
The DRV8824 stepper motor driver carrier ships with one 1×16-pin breakaway 0.1" male header. The headers can be soldered in for use with solderless breadboards or 0.1" female connectors. You can also solder your motor leads and other connections directly to the board.
The driver requires a motor supply voltage of 8.2 – 45 V to be connected across VMOT and GND. This supply should have appropriate decoupling capacitors close to the board, and it should be capable of delivering the expected stepper motor current.
Warning: This carrier board uses low-ESR ceramic capacitors, which makes it susceptible to destructive LC voltage spikes, especially when using power leads longer than a few inches. Under the right conditions, these spikes can exceed the 45 V maximum voltage rating for the DRV8824 and permanently damage the board, even when the motor supply voltage is as low as 12 V. One way to protect the driver from such spikes is to put a large (at least 47 µF) electrolytic capacitor across motor power (VMOT) and ground somewhere close to the board.
Four, six, and eight-wire stepper motors can be driven by the DRV8824 if they are properly connected; a FAQ answer explains the proper wirings in detail.
Warning: Connecting or disconnecting a stepper motor while the driver is powered can destroy the driver. (More generally, rewiring anything while it is powered is asking for trouble.)
Each pulse to the STEP input corresponds to one microstep of the stepper motor in the direction selected by the DIR pin. These inputs are both pulled low by default through internal 100kΩ pull-down resistors. If you just want rotation in a single direction, you can leave DIR disconnected.
The chip has three different inputs for controlling its power states: RESET, SLEEP, and ENBL. For details about these power states, see the datasheet. Please note that the driver pulls the SLEEP pin low through an internal 1MΩ pull-down resistor, and it pulls the RESET and ENBL pins low through internal 100kΩ pull-down resistors. These default RESET and SLEEP states are ones that prevent the driver from operating; both of these pins must be high to enable the driver (they can be connected directly to a logic “high” voltage between 2.2 and 5.25 V, or they can be dynamically controlled via connections to digital outputs of an MCU). The default state of the ENBL pin is to enable the driver, so this pin can be left disconnected.
To achieve high step rates, the motor supply is typically much higher than would be permissible without active current limiting. For instance, a typical stepper motor might have a maximum current rating of 1 A with a 5Ω coil resistance, which would indicate a maximum motor supply of 5 V. Using such a motor with 12 V would allow higher step rates, but the current must actively be limited to under 1 A to prevent damage to the motor.
The DRV8824 supports such active current limiting, and the trimmer potentiometer on the board can be used to set the current limit. You will typically want to set the driver’s current limit to be at or below the current rating of your stepper motor. One way to set the current limit is to put the driver into full-step mode and to measure the current running through a single motor coil without clocking the STEP input. The measured current will be 0.7 times the current limit (since both coils are always on and limited to approximately 70% of the current limit setting in full-step mode).
Another way to set the current limit is to measure the voltage on the “ref” pin and to calculate the resulting current limit (the current sense resistors are 0.330Ω). The ref pin voltage is accessible on a via that is circled on the bottom silkscreen of the circuit board. The current limit relates to the reference voltage as follows:
Current Limit = VREF * 0.61
So, for example, if you have a stepper motor rated for 0.5 A, you can set the current limit to 0.5 A by setting the reference voltage to 0.82 V.
Note: The coil current can be very different from the power supply current, so you should use the current measured at the power supply to set the current limit. The appropriate place to put your current meter is in series with one of your stepper motor coils.
The DRV8824 driver IC has a maximum current rating of 1.6 A per coil, but the current sense resistors further limit the maximum current to 1.2 A, and the actual current you can deliver depends on how well you can keep the IC cool. The carrier’s printed circuit board is designed to draw heat out of the IC, but to supply more than approximately 0.75 A per coil, a heat sink or other cooling method is required.
This product can get hot enough to burn you long before the chip overheats. Take care when handling this product and other components connected to it.
The current resistors R2 and R3 are 0.330 Ω on the DRV8824 carrier version. This schematic is also available as a downloadable pdf (196k pdf).