Pololu Qik 2s12v10 - Manual (Page 9)

Qik 2s12v10 TTL serial connection example
(transmit and receive).
Qik 2s12v10 RS-232 serial connection example
(qik receive only).
Both RX and SIN connect to the same serial port on the qik, so you should not use both of these inputs
simultaneously. Don’t forget to connect your serial source’s ground to the qik’s ground!
Reset
The reset line, RST, is an active-low input, which means that it resets the qik when driven low. This pin is
internally pulled to 5 V, so many applications can leave this pin disconnected.
Error
The error line, ERR, is an output that is connected to the red error LED and drives high (5 V) in response to an
error (which in turn lights the LED). Once an error occurs, the pin outputs high until a serial command is issued to
read the error byte, at which point the pin goes to a high-impedance state that is pulled low through the LED. This
allows you to connect the error lines of multiple qiks to the same digital input. Please note, however, that doing
this will cause the error LEDs of all connected qiks to turn on whenever one qik experiences an error; the ERR
output of the qik experiencing the error will drive the LEDs of any other qiks it is connected to, even though they
are not experiencing error conditions themselves. For more information on the possible error conditions, please
see
Section 5.c . If you don’t care about error detection, you can leave this pin disconnected.
5V (out)
This line connects to the 5 V output of the qik’s voltage regulator and can be used to power additional electronics
in your system. It can safely supply up to 70 mA beyond what the board draws when VIN is 16 V. The closer the
input voltage is to 5 V, the more current the regulator can deliver without overheating.
VIN (out)
This is a convenient connection point to the input voltage that can be used as a power source for additional
electronics. Note that this pin is not intended to handle high currents, so it should not be used to power the qik
(use the large VIN and GND pads on the other side of the board for this). Do not attempt to draw more than 1 A
from this pin.
Connecting to a 3.3 V Microcontroller
The logic components on the qik 2s12v10 run at 5 V, but it is still possible to interface with a 3.3 V
microcontroller. The RX high input threshold is 3 V, so you can directly connect your microcontroller’s transmit
line to the qik’s TTL serial receive line (i.e. no additional components are required for sending commands to the
qik from a 3.3 V MCU).
If your microcontroller digital inputs are 5V-tolerant, you can make direct connections to the ERR and TX outputs
and RST input, which is weakly pulled to 5 V on the qik. If not, you can leave these optional outputs unconnected,
or you can use external components to decrease the voltage to a range your MCU can handle. A simple way to
accomplish this is by placing voltage dividers between each qik output and your MCU.
Qik 2s12v10 User's Guide © 2001–2012 Pololu Corporation
3. Connecting the Qik Page 9 of 33