Overview
The
jrk 21v3 is a versatile, general-purpose motor controller that supports a
variety of interfaces, including USB. The broad operating range from 5 V to 28 V
and continuous output current of 3 A (5 A peak) allow this board to control most
small DC brushed motors. Analog voltage and tachometer (frequency) feedback
options allow quick implementation of closed-loop servo systems, and a free
configuration utility (for Windows 7, Vista, or Windows XP) allows easy
calibration and configuration through the USB port.
Key improvements over competing products and earlier Pololu motor controllers
with feedback include:
- USB connectivity with emulated serial (COM) port
allows direct motor control from a PC.
- Ultrasonic PWM to eliminate
switching-induced motor shaft hum or whine.
- Robust, high-speed
communication protocol with user-configurable error condition response.
-
High internal resolution (12 bits) for smooth and flexible calibration to
various input and feedback devices.
- Current sensing and limiting.
-
Reversed power protection.
- Field-upgradeable firmware.
Main Features of the Jrk 21v3
 |
- Simple bidirectional control of one DC brush motor.
- 5 V to 28 V
operating supply range.
- 3 A maximum continuous current output (5 A
peak).
- Four communication or control options:
- USB interface for
direct connection to a PC.
- Full-duplex, TTL-level asynchronous serial
interface for direct connection to microcontrollers or other embedded
controllers.
- Hobby radio control (RC) pulse width (PWM) interface for
direct connection to an RC receiver or RC servo controller.
- 0–5 V
analog voltage interface for direct connection to potentiometers and analog
joysticks
- Two closed-loop feedback options:
- 0–5 V analog
voltage.
- Frequency/tachometer digital input up to 2 MHz with 1 ms PID
period.(Open-loop control with no feedback also available.)
 |
 |
Simple configuration and calibration over USB with free configuration program
(Windows 7, Vista, and Windows XP compatible).
- Configurable parameters
include:
- PID period and PID constants (feedback tuning
parameters).
- Maximum current.
- Maximum duty cycle.
-
Maximum acceleration.
- Error response.
- Input calibration
(learning) for analog and RC control.
- Optional CRC error detection
eliminates communication errors caused by noise or software faults.
-
Reversed power protection.
- Field-upgradeable firmware.
- Optional
feedback potentiometer disconnect detection.
Specifications
| Motor
channels: |
1 |
| Operating
voltage: |
5
– 28 V |
| Continuous
output current: |
3 A |
| Peak
output current: |
5 A |
| Auto-detect
baud rate range: |
300
– 115,200 bps |
| Available
fixed baud rates: |
300
– 115,200 bps |
| Available
PWM frequencies: |
20 kHz,
5 kHz |
| Reverse
voltage protection?: |
Yes |
| USB
connector style: |
USB
Mini-B |
The
jrk 21v3 is the smaller of two jrk motor controllers. For a higher-power
version, see the jrk 12v12.
Included Hardware
The
jrk ships with a 14×1 straight 0.100" male header strip and two 3.5mm, 2-pin
terminal blocks. To provide maximum flexibility, none of these parts are
soldered to the board.
For
the most compact installation, you can solder wires directly to the jrk pads
themselves and skip using the included hardware. The included hardware allows
you to make less permanent connections. You can break the 14×1 header strip into
an 8×1 piece and two 3×1 pieces and solder these strips into the jrk’s I/O
pads.
Dimensions
| Size: |
1.35"
x 1.35" x 0.4"1 |
| Weight: |
0.23
o |
General specifications
| Motor
driver: |
MC33926 |
| Motor
channels: |
1 |
| Control
interface: |
USB;
non-inverted TTL serial;
RC
servo pulses; analog voltage2 |
| Minimum
operating voltage: |
5
V |
| Maximum
operating voltage: |
28
V |
| Continuous
output current per channel: |
3
A |
| Peak
output current per channel: |
5
A |
| Current
sense: |
0.5
V/A3 |
| Maximum
PWM frequency: |
20
kHz |
| Minimum
logic voltage: |
4
V4 |
| Maximum
logic voltage: |
5
V |
| Reverse
voltage protection?: |
|
Notes:
- Without included
hardware.
- Autodetects baud rates between 300 and 115,200 bps, or can be
set to any fixed baud rate in this range.
- Current readings are converted
to a digital number from 0-255.
- In RC mode, the pulses can be as low as
2V.
)
