Pololu Qik 2s12v10 - Manual (Page 12)

the silkscreen labels). This sets the baud rate to a predetermined value, as described in the table below, and the qik
skips the automatic baud detection phase that normally occurs on start-up.
BAUD1
Jumper
BAUD2
Jumper
Baud Mode
OFF OFF auto-detect baud rate (1200 – 115,200 bps)
ON OFF fixed baud rate at 115,200 bps
OFF ON fixed baud rate at 38,400 bps
ON ON fixed baud rate at 9,600 bps
Enable-CRC Mode
The jumper labeled CRC on the bottom of the qik enables cyclic redundancy check (CRC) mode when the
shorting block is in place. This allows you to increase the robustness of your qik connection through the addition
of a CRC error-checking byte to the end of the command packets you send to the qik. The default behavior of
the qik is to simply respond to a command packet once it receives the last byte. Grounding pin CRC (the circular
pad right next to the “CRC” silkscreen label) causes the qik to expect an additional CRC byte at the end of every
command packet. The CRC byte is the result of a CRC-7 computation on the entire command packet, as described
in
Section 6 . If this byte does not match the expected CRC, the qik ignores the command and uses the ERR pin
to announce a CRC error. When in this mode, the green heartbeat LED will flicker twice per heartbeat rather than
the single flash that occurs when CRC error checking is disabled.
Demo Mode
If you short pin BAUD1 to pin BAUD2 (the circular pads right next to the silkscreen labels) and reset the qik, it
enters demo mode and remains in demo mode for as long as the short is maintained. Demo mode gives you an easy
way to test your qik and troubleshoot your application for potential problems. In demo mode, the qik smoothly
ramps motor M0 from stopped to full-speed forward to full-speed reverse to stopped again over a few seconds. It
then does the same for motor M1. The red (error) LED is on while motor M0 is active and off while motor M1 is
active. The green (status) LED is on while the active motor is driving forward and off while the active motor is
driving in reverse. The motor indicator LEDs also light in response to the motor driver outputs.
Demo mode can help you determine before you’ve even written any code if you have an issue with your power
supply, such as insufficient ability to supply the current your motors are drawing or interference from motor noise.
While in demo mode, any serial data that is received by the qik on the RX line is echoed on the TX line, giving
you an easy way to test your serial connection. It accomplishes this by repeatedly checking the state of the serial
input pin and setting the state of the output pin to match. This process works reliably at low baud rates, but it is
not fast enough to keep up well at higher baud rates, which can result in an echoed byte that does not match the
one you transmitted.
3.e. Indicator LEDs and Phases of Operation
LED Overview
The qik has seven LEDs that are used to provide feedback about its state of operation:
• Power LED ( blue ): This blue LED is lit when the board is receiving power. It is located on the logic side
of the board.
• Status LED ( green ): This green LED provides a heartbeat to let you know that your qik is alive and what
state the qik is in, and it also acts as a serial activity indicator. It is located on the logic side of the board near
the jumpers.
Qik 2s12v10 User's Guide © 2001–2012 Pololu Corporation
3. Connecting the Qik Page 12 of 33