Digi International Inc XBEEPRO2 Manual Do Utilizador

Note – The signal-ended ADC measurements are limited in their range and only guaranteed for accuracy in 
the range 0 to VREFI. The nature of the ADC’s internal design allows for measurements outside of this range 
(+/- 200mV), but the accuracy of such measurements are not guaranteed.

The S2B modules that have the programmable option populated 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 EM250 or the MC9S08QE micro (see Block Diagram for details). The EM250 by default has control of 
certain lines. These lines can be released by the EM250 by sending the proper command(s) to disable the 
desired DIO line(s) (see XBEE Command Reference Tables).

In order for the secondary processor to sample with ADCs, the XBEE pin 14 (VREF) needs to 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 (Pin 8).

V

IL

Input Low Voltage

All Digital Inputs

-

- 

0.2 * VCC

V

V

IH

Input High Voltage

All Digital Inputs

0.8 * VCC

- 

 -

V

V

OL

Output Low Voltage

VCC >= 2.7 V

-

-

0.18*VCC

V

V

OH

Output High Voltage

 VCC >= 2.7 V

0.82*VCC

-

-

V

I

IIN

Input Leakage Current

V

IN

 = VCC or GND, all inputs, per pin

-

-

0.5uA

uA

I

OHS

Output source current (standard) 

All digital outputs except

RSSI/PWM, DIO10, DIO4

4

mA

I

OHH

Output source current (high 

current)

RSSI/PWM, DIO10, DIO4 digital outputs

8

mA

I

OLS

Output sink current (standard

All digital inputs except

RSSI/PWM, DIO10, DIO4

4

mA

I

OLH

Output sink current (high current)

RSSI/PWM, DIO10, DIO4 digital outputs

8

mA

I

OH + 

I

OL

Total output current for all I/O pins

All digital outputs

40

mA

V

REFI

VREF Internal

EM250 has an internal reference that is 

fixed

1.19

1.2

1.21

V

V

IADC

ADC input voltage range

0

VREFI

V

R

IS 

Input impedance

When taking a sample

1

M Ohm

R

I

Input Impedance

When not taking a sample

10

M Ohm