Hardware
Module operation for the programmable variant
XBee 868LP RF Modules User Guide
28
Number
Description
1
Use multiple vias to help eliminate ground variations.
2
Put a solid ground plane under RF trace to achieve the desired impedance.
Module operation for the programmable variant
The modules with the programmable option have a secondary processor with 32k of flash and 2k of
RAM. This allows module integrators to put custom code on the XBee module to fit their own unique
needs. The DIN, DOUT, RTS, CTS, and RESET lines are intercepted by the secondary processor to allow
it to be in control of the data transmitted and received. All other lines are in parallel and can be
controlled by either the internal microcontroller or the MC9SO8QE micro; see the block diagram in
for details. The internal microcontroller by default has control of certain lines. The internal
microcontroller can release these lines by sending the proper command(s) to disable the desired DIO
line(s). For more information about commands, see
.
For the secondary processor to sample with ADCs, the XBee must be connected to a reference
voltage.
Digi provides a bootloader that can take care of programming the processor over-the-air or through
the serial interface. This means that over-the-air updates can be supported through an XMODEM
protocol. The processor can also be programmed and debugged through a one wire interface BKGD .
