SparkFun: KIT-11087

Description: Under-powering a digital device can sometimes have pretty nasty consequences. Brown-out conditions can cause memory to get written or overwritten in odd ways, can cause unexpected behavior in connected systems and just generally screw up your day. One way to avoid this is to keep an eye on your battery voltage and turn off the system before it gets too low (or plug it in). We’ve whipped up a little board to help you out with this situation: the “Uh-oh” battery level indicator.

At the heart of the “Uh-oh” board is the TL431ACLPG shunt regulator diode. The reference voltage can be adjusted by using the trimpot on board. When the battery connected to the board reaches that voltage, the shunt allows current to flow through the LED, alerting you to a low battery situation. In order to set the appropriate reference voltage, you can use the formula found in the schematic to calculate your desired resistance and set it using the trimpot and a multimeter measuring resistance across the provided test points.

This board comes as a “bag of parts” kit. All of the parts are through-hole and it shouldn’t take long to solder together. The footprint of each part is clearly marked on the PCB to help you throw it together.

Kit Includes:

• “Uh-oh” Through-hole PCB
• 10mm Diffused Green LED
• JST Wire Assembly
• TL431ACLPG IC
• JST Right-Angle Connector
• 10K Trimpot
• 330 Ohm Resistor

Don Luc

SparkFun: ROB-10267

Description: The EasyDriver is a simple to use stepper motor driver, compatible with anything that can output a digital 0 to 5V pulse (or 0 to 3.3V pulse if you solder SJ2 closed on the EasyDriver). EasyDriver requires a 7V to 20V supply to power the motor and can power any voltage of stepper motor. The EasyDriver has an on board voltage regulator for the digital interface that can be set to 5V or 3.3V. Connect a 4-wire stepper motor and a microcontroller and you’ve got precision motor control! EasyDriver drives bi-polar motors, and motors wired as bi-polar. I.e. 4,6, or 8 wire stepper motors. On this version (v4.4) we fixed the silk error on the min/max adjustment.

This is the newest version of EasyDriver V4 co-designed with Brian Schmalz. It provides much more flexibility and control over your stepper motor, when compared to older versions. The microstep select (MS1 and MS2) pins of the A3967 are broken out allowing adjustments to the microstepping resolution. The sleep and enable pins are also broken out for further control.

Note: Do not connect or disconnect a motor while the driver is energized. This will cause permanent damage to the A3967 IC.

Note: This product is a collaboration with Brian Schmalz. A portion of each sales goes back to them for product support and continued development.

Features:

• A3967 microstepping driver
• MS1 and MS2 pins broken out to change microstepping resolution to full, half, quarter and eighth steps (defaults to eighth)
• Compatible with 4, 6, and 8 wire stepper motors of any voltage
• Adjustable current control from 150mA/phase to 750mA/phase
• Power supply range from 7V to 20V. The higher the voltage, the higher the torque at high speeds

Don Luc

SparkFun: DEV-09530

Description: The SparkFun OpenLog is an open source data logger. Simple to use, simple to change. We wanted to create a serial logger that just worked. Power up this device and it will start logging any received serial data at 9600bps. Sending Ctrl+z three times will drop out of logging and in to command mode. ‘new’ will create a new file. ‘md’ makes a directory. ‘?’ brings up the list of commands. OpenLog doesn’t do a lot, but it does log serial streams extremely well.

Example:

 >new testfile.txt  
 >append testfile.txt  
 <(send large amounts of text followed by three ctrl+z characters)

That’s really it! OpenLog firmware is open source and is based on Bill Greiman’s sdfatlib. OpenLog currently supports FAT16 and FAT32 microSD cards (we’ve tested up to 64GB!).

All the design files (schematic, PCB layout, firmware) are open source released under the CC-SA v3 license and are available through GitHub.

Note: New firmware is available which allows the OpenLog to be used in Arduino 1.0 and also allows for higher baud rates. Check the links below for more information.

Features:

• Log to low-cost microSD FAT16/32 cards up to 16GB
• Simple command interface
• Edit config.txt file from a computer to change baud rate and other system settings
• Three modes:
  NewLog creates a new log every power up and immediately starts logging
  SeqLog appends a file called “SeqLog.txt” at every power up and immediately starts logging
  Command mode starts OpenLog at a command prompt at power up
• Configurable baud rates (2400 to 115200bps)
• Configure unit through config file or the menu system
• Power, ground, and RX-I are the minimum connections
• Reprogrammable ATmega328 using the Arduino IDE
• Two LEDs indicate writing status
• Input voltage from 3.3V to 12V
• 2mA idle, 6mA at maximum recording rate

Dimensions: 0.16 x 0.6 x 0.75″ (4 x 15 x 19mm)

Don Luc