Download - Phi Education

Product Manual
Lynx
Version 1.0
Phi Robotics Research Pvt. Ltd.
www.phi-robotics.com
Table of Contents
1
Introduction ................................................................................................................................................... 2
2
Board Features ............................................................................................................................................... 2
3
Specifications ................................................................................................................................................. 2
3.1
4
PCB Details ............................................................................................................................................ 2
Hardware Connections ................................................................................................................................... 3
4.1
Power Supply ......................................................................................................................................... 3
4.2
Motor Connections ................................................................................................................................ 3
4.3
Microcontroller Connections................................................................................................................. 3
4.4
Rotating the Motor ............................................................................................................................... 4
4.5
LEDs....................................................................................................................................................... 4
5
Pseudo Code ................................................................................................................................................... 5
6
Reference ....................................................................................................................................................... 5
1
Introduction
Lynx is a micro stepping stepper motor driver board powered by A3977. It has a built-in translator and is
designed to operate bipolar stepper motor in full, half, quarter and one-eighth step-modes. Lynx has motor
supply voltage of 8V to 35V and maximum current rating of ±2.5 A. The A3977 includes a fixed off-time current
regulator that has the ability to operate in slow, fast, or mixed decay modes. This current-decay control
scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation. The
advantage of having the translator and driver in one package is minimizing the number of control lines. This
single board can replace two or more devices in many designs thereby reducing cost of the system. The board
interface is ideal for applications where a complex microprocessor is unavailable or overburdened.
Lynx is compatible with Phi Robotics xLynx-CB board.
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Board Features
Supports up to 8 micro steps per full step
10 pin header for connection
Specifications
Current output rating: ±2.5 A
Drain to source resistance (ON): 0.45 Ω source, 0.36 Ω sink
Logic supply voltage: 3V -5.5V
Motor supply voltage: 8V to 35V
3.1 PCB Details
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PCB size: 50.8 mm x 38.1 mm
PCB type: FR4
Board thickness: 1.6 mm
Solder mask: Black
Surface finish: Immersion gold
4
Hardware Connections
Figure 1-Lynx top view
4.1 Power Supply
Lynx requires 3V to 5.5V for logic supply. Logic supply pins are provided on connector J1. Lynx supports motor
supply voltage of 8V to 35V. Terminal T2 is provided for the same.
4.2 Motor Connections
Terminals T2 and T3 are for stepper motor connections. Coil A of the motor should be connected to terminal
T2 and coil B should be connected to T3.
4.3 Microcontroller Connections
A 10 pin FRC header (J1) is provided for connecting Lynx with microcontroller. The connector has logic power
supply pins, motor direction pin (DIR), step size selection pins (MS1, MS2), step pin to rotate motor by one
step and control pins like reset, sleep and home. Lynx requires only GPIO interface and no special peripheral
like ADC, I2C or SPI. Figure 2 shows pin layout for connector J1.
Figure 2 - J1 header pin layout
4.4 Rotating the Motor
For rotating stepper motor first, Lynx should be set in active mode by setting sleep and reset pins high, as
these pins are active low. Step size for motor can be selected using the pins MS1 and MS2. Table 1 shows MS1MS2 setting for step size selection.
Table 1 - Step size selection
Step Size
Full step
Half step
Quarter step
One eighth step
MS2
Low
Low
High
High
MS1
Low
High
Low
High
The direction of the motor can be set using DIR pin. Setting DIR pin high will rotate motor in clockwise
direction whereas, setting pin low will rotate the motor in anti-clockwise direction. After setting the board in
active mode and setting appropriate step size, a low to high transition on STEP pin will drive the motor by
single step. User can provide pulses with appropriate frequency to achieve the required motor speed.
4.5 LEDs
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HOME LED: Indicates the initial condition of the translator
POWER LED: Logic power supply indicator
BAT LED: Motor battery supply indicator
5
Pseudo Code
/*
Following motor pins should be connected to
microcontroller GPIO pins
DIR: for setting motor direction
MS1, MS2: For setting step size
RESET: For resetting the driver
SLEEP: To enable driver sleep mode to save power
STEP: To rotate motor by one step
*/
void lynxInit(void)
{
gpioSet(RESET);
// set active mode
gpioSet(SLEEP);
// disable sleep mode
// user can set the step size according to application requirement
lynxSetStepSize(FULL_STEP);
}
void lynxSingleStep(void)
{
gpioSet(STEP);
delay_us(1);
gpioSet(STEP);
}
// give pulse to step pin of lynx
// STEP pulse width should be minimum 1 us
void lynxRun(uint8_t dir, uint32_t stepCount, uint32_t delay)
{
// set motor rotation direction
lynxSetDirection(dir);
loop(stepCount)
{
// generate STEP pules continuously to keep running the motor
lynxSingleStep();
// use delay to set the motor speed
// minimum delay should be 1 us
// as maximum step frequency can be 500KHz
delay_us(delay);
}
}
6
Reference
A3977 Datasheet: http://www.allegromicro.com/en/Products/Motor-Driver-And-Interface-ICs/BipolarStepper-Motor-Drivers/A3977.aspx
Phi Robotics Research Pvt. Ltd.
www.phi-robotics.com