Copyright © 2015 Robot Circuits, LLC
19
RCAT-1A Rev A3 Designer’s manual
Serious Power for the Serious Designer
Notes
Connector J2 provides access to the TWI by you external devices. Pullups R4 and R5 are provided relieving you of
the need to pull the lines to Vcc. Also note the 3.3Vdc to 5Vdc level shifters (Q1/Q2) enable the connection of
3.3Vdc TWI devices to J2 pins 5 and 7. The example software solution provided with your RCAT™ board
configures the TWI for operation at 400KHz, so keep this in mind when connecting your device(s) and using the
example solution provided.
1M-bit serial EEPROM
The RCAT™ board includes a 1M-bit Serial EEProm chip, the STMicro M24M01-RMN6TP, for use however you
desire. This chip is managed via the TWI (described earlier). The schematic for this device is also shown above.
Please consult the manufacturer’s datasheets (
M24M01-R
) for details on how to properly use this device.
The example software solution provided with your RCAT™ board includes examples of how to read and write
from/to this device. Please note that since it hangs on the TWI, which is accessible from the outside world, you
could turn off any control from the CPU and use your own external control mechanisms to read and write this
chip.
Accelerometer
Onboard the RCAT™ is an ADXL345 accelerometer chip made by Analog Devices.
Get datasheet here
. The need
for an accelerometer in robotics applications is so commonplace that we decided to relieve our users from the
chore of buying and attaching a separate module dedicated to this purpose. This chip is a very powerful
accelerometer that features 3-axis measurement of attitudinal and inertial situations that make it possible to do
very accurate reckoning of position, tracking of motion and determination of pitch/roll/yaw in almost limitless
ways. The axis orientation of the chip is noted on the silkscreen of the RCAT™ as shown here:
Figure 14
