Serial settings – Pololu Simple User Manual
Page 58
Note: TTL serial is not the same as RS-232 serial. You must use an inverter and level shifter such as a
MAX232 or a
if you want to interface an
RS-232 device with the Simple Motor Controller. Connecting an RS-232 device directly to the Simple
Motor Controller can permanently damage it.
6.1. Serial Settings
The behavior of the Simple Motor Controller’s serial interface is determined by a number of settings, almost all of
which can be configured under the Input Settings tab of the Simple Motor Control Center:
The serial settings in the Input Settings tab of the Pololu Simple Motor
Control Center.
Serial Mode: The Serial Mode determines which protocols the Simple Motor Controller will accept.
• Binary: In this mode, the controller expects command packets comprised of a series of bytes that conform to
the Compact, Pololu, or Mini SSC protocol formats (see
for more information on these protocols).
The Binary-protocol commands are more compact than their ASCII-protocol counterparts, so they can be
transmitted faster, and they let you send commands addressed to a particular device number, so this mode should
be used when multiple devices daisy-chained together on the same serial line. Note that some of the other serial
settings (documented below) are only available in this mode.
• ASCII: In this mode, the controller expects command packets comprised of ASCII characters, which makes
the commands potentially more friendly to beginners since they look like character strings rather than seemingly
random sets of bytes. Also, the ASCII protocol makes it easy to send commands to the Simple Motor Controller
from a terminal program. See
for more information on the ASCII protocol.
CRC Mode: When enabled, the Simple Motor Controller requires a cyclic redundancy check (CRC) byte at the
end of every Binary Mode serial command packet, which helps ensure that the controller won’t misinterpret noisy
commands or act up when presented with a stream of random serial bytes (see
for more information on
CRCs). CRC error detection is only available when the Serial Mode is “Binary”; it is disabled when the Serial Mode
is “ASCII”. There are three possible CRC modes:
• Disabled: CRC error detection is not enabled, and CRC bytes should not be added to the end of command
packets.
Pololu Simple Motor Controller User's Guide
© 2001–2014 Pololu Corporation
6. Using the Serial Interface
Page 58 of 101