Updating the trex jr's firmware, Current firmware versions, Updating firmware – Pololu TReX Jr User Manual
Page 21: Updating the trex jr’s firmware
6. Updating the TReX Jr's Firmware
Current Firmware Versions
• Our
most
recently
released
firmware
update
for
the
TReX
Jr
motor
controller
is
(161k trx) (version 1.2). This version
fixes a bug that prevented baud rates of 38.4 and 28.8 kbps from working in versions 1.0 and 1.1. All other
supported baud rates work properly in firmware versions 1.0 and 1.1, so if your TReX Jr does not have version
1.2 firmware and you do not need communicate serially at 38,400 or 28,800 bps, you do not need to update
your firmware to 1.2. Version 1.2 also adds a new configuration parameter that lets you optionally delay the
TReX Jr’s serial responses by 1ms so that slower microcontrollers, such as the Basic Stamp, won’t miss the
first byte of the TReX Jr’s response. Previously, if you wanted such a delay, you needed to use firmware
version 1.1; if you didn’t want this delay, you needed to use firmware version 1.0. Please note that you should
upgrade
your
(294k zip) to version 090923 or later prior to updating your
firmware to version 1.2. If you have an older version of the TReX Configurator installed, you should manually
uninstall it first using the Add/Remove Programs control panel.
• The
firmware
that
comes
preloaded
on
every
TReX
Jr
motor
controller
is
(137k trx).
• We have released an alternate firmware version:
(138k trx). Please note that this alternate version is not considered an upgrade over
the original version 1.0. Rather, version 1.1 exists to improve serial communication with controllers that require
a delay between transmitting and receiving, such as the Basic Stamp. Firmware version 1.1 inserts a 1 ms delay
between the last byte of a received command packet and the first byte of the TReX Jr’s transmitted response,
which should give your controller enough time to switch from serial-out mode to serial-in mode. Without this
delay, some slower controllers will miss the first byte of the TReX Jr’s response, especially if you are
communicating at higher baud rates. If your controller can simultaneously transmit and receive, or if it does not
take much time to switch between serial-out and serial-in mode, you should use firmware version 1.0 as this
will increase the rate at which you can communicate with and control your TReX Jr.
Updating Firmware
To update the firmware, you need to put your TReX Jr into firmware-update mode and then send the new binary
firmware file, which you can do using the
(294k zip) or a terminal program. We recommend you read through
the following procedure before performing the update.
1. Turn off power to your TReX Jr.
2. Put the TReX Jr into Serial Mode by removing the Mode jumper.
3. Ground the TTL Serial Out (SO) pin by attaching the Learning-Mode/Firmware-Upgrade jumper.
4. Attach the Mix jumper.
5. Restore power to the TReX Jr; the status LEDs should alternately flash red and green.
6. Remove the Mix jumper; the status LEDs should alternate faster.
7. Remove the Learning-Mode/Firmware-Upgrade jumper; the green status LED should now briefly flash
every second.
8. Reconnect your TReX Jr’s serial cable to establish a connection between your TReX Jr and your computer.
Pololu TReX Jr User's Guide
© 2001–2009 Pololu Corporation
6. Updating the TReX Jr's Firmware
Page 21 of 23