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→Entrées de contrôle
The chip has two different inputs for controlling its power states: {{overline|SLEEP}} and {{overline|ENBL}}. For details about these power states, see the datasheet. Please note that the driver pulls both of these pins low through internal 500 kΩ pull-down resistors. The default {{overline|SLEEP}} state prevents the driver from operating; this pin must be high to enable the driver (it can be connected directly to a logic “high” voltage between 2.5 V and 5 V, or it can be dynamically controlled by connecting it to a digital output of an MCU). The default state of the {{overline|ENBL}} pin is to enable the driver, so this pin can be left disconnected.
The chip has two different inputs for controlling its power states: {{overline|SLEEP}} and {{overline|ENBL}}. For details about these power states, see the datasheet. Please note that the driver pulls both of these pins low through internal 500 kΩ pull-down resistors. The default {{overline|SLEEP}} state prevents the driver from operating; this pin must be high to enable the driver (it can be connected directly to a logic “high” voltage between 2.5 V and 5 V, or it can be dynamically controlled by connecting it to a digital output of an MCU). The default state of the {{overline|ENBL}} pin is to enable the driver, so this pin can be left disconnected.
{{POLImage|MP6500-02.png|250px|Schematic of nSLEEP and nFAULT pins on MP6500 carrier.}}
{{POLImage|MP6500-02.png|250px|Schematic of nSLEEP and nFAULT pins on MP6500 carrier.}}
The MP6500 also features an open-drain {{overline|FAULT}} output that drives low whenever the H-bridge FETs are disabled as the result of over-current protection, over-voltage protection, thermal shutdown, or under-voltage lockout protection. The carrier board connects this pin to the {{overline|SLEEP}} pin through a 10 kΩ resistor that acts as a {{overline|FAULT}} pull-up whenever SLEEP is externally held high, so no external pull-up is necessary on the {{overline|FAULT}} pin. Note that the carrier includes a 1.5 kΩ protection resistor in series with the {{overline|FAULT}} pin that makes it is safe to connect this pin directly to a logic voltage supply, as might happen if you use this board in a system designed for the pin-compatible {{pl|349|A4988 carrier}}. In such a system, the 10 kΩ resistor between {{overline|SLEEP}} and {{overline|FAULT}} would then act as a pull-up for {{overline|SLEEP}}, making the MP6500 carrier more of a direct replacement for the A4988 in such systems (the A4988 has an internal pull-up on its SLEEP pin).
{{ambox|text=As a consequence of the connection between {{overline|SLEEP}} and {{overline|FAULT}}, active faults can pull the {{overline|SLEEP}} pin low (below 2.1 V) if it is not externally pulled up strongly enough. We recommend any pull-up resistor used with {{overline|SLEEP}} be 4.7 kΩ or stronger (or just connect {{overline|SLEEP}} directly to VCC).}}
== Limitation du courant ==
Vidéo de Pololu (anglais) concernant la limitation de courant.
To achieve high step rates, the motor supply is typically 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 5 Ω coil resistance, which would indicate a maximum motor supply of 5 V. Using such a motor with 9 V would allow higher step rates, but the current must actively be limited to under 1 A to prevent damage to the motor.
The MP6500 supports such active current limiting, and the trimmer potentiometer on the board can be used to set the current limit:
{{POLImage|MP6500-03.png|600px|Limitation de courant en fonction de la position du potentiomètre sur le contrôleur MP6500.}}
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 VREF voltage and calculate the resulting current limit. The VREF voltage is accessible on a via that is circled on the bottom silkscreen of the circuit board. The current limit relates to VREF as follows:
{{POLImage|MP6500-04.png|600px|Limitation de courant en fonction de la position du potentiomètre sur le contrôleur MP6500.}}
So, the current limit in amps (A) is equal to 3.5 times the VREF voltage in volts (V), and if you have a stepper motor rated for 1 A, for example, you can set the current limit to about 1 A by setting the reference voltage to about 0.28 V. In practice, we have often observed the actual current limit to be about 10% (sometimes up to 15%) lower than what the equation and graph show.
The I1 and I2 pins are not used on this version of the MP6500 Stepper Motor Driver Carrier, and any signals applied to these pins will have no effect on the operation of the driver.
{{ambox|text=The coil current can be very different from the power supply current, so you should not 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. If the driver is in full-step mode, both coils will always be on and limited to approximately 70% of the current limit setting. If your driver is in one of the microstepping modes, the current through the coils will change with each step, ranging from 0% to 100% of the set limit. See the MP6500 datasheet for more information.}}
== Dissipation de puissance ==
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== Où Acheter ==
== Où Acheter ==