Specifications

78
Digital I/O
Input High
Voltage (V
IH
)
0.5 x V
DD
______
V
DD
+ 0.3
V
Input Low
Voltage (V
IL
)
-0.3
______
0.22 x V
DD
V
Table 23 MRF24J40MB Recommended Operating Conditions (Reprinted
with permission from MicroChip®)
One of the great features of the MRF24J40MB is the low current consumption
that allows the RF transceiver module to ultimately consume less power. The
module has three modes: Sleep, Transmit (TX), and Receive (RX). For the sleep
mode when the sleep clock is disabled, the MRF24J40MB uses 5 uA of current.
At the maximum output power, in the transmit state, it uses 130 mA of current,
while in the receive mode, only 25 mA is consumed.
3.2.2 IEEE 802.11b™ RF Transceiver Module
(MRF24WB0MA)
The main microcontroller for our system needs to be able to connect to the
internet. One solution that we researched was having a RF transceiver that was
compatible with IEEE 802.11 protocols. Looking at Microchip‟s ® wireless
solutions, the MRF24WB0MA Wi-Fi radio transceiver module fit many of our
requirements.
The MRF24WB0MA has many features that work well with our system. The
MRF24WB0MA is a 36 pin surface mountable module that‟s dimensions are 21
mm x 31 mm. It operates on the ISM 2.400 – 2.483.5 GHz band, which is in the
802.11 b protocol. The module requires a low supply voltage, 2.7V – 3.6V (3.3V
typical), the standard operating voltage range of a RF transceiver module. This
will be beneficial, as other components also operate off of a similar range, with
3.3V being the usual measurement.
With balanced receiver and transmitter characteristics, the MRF24WB0MA can
offer different modes of low current consumption depending on what is called for
by the user. In Receive (RX) mode, only 85 mA is used, while in the Transmit
(TX) mode, only 154 mA. In Hibernate, less than 01 uA is used, while the Sleep
mode uses 250 uA.
The MRF24WB0MA module is designed to be used with Microchip‟s ® TCIP/IP
software stack, as well many Microchip® microcontroller families (PIC18, PIC24,
dsPIC33, and the PIC32). The TCIP/IP software stack is available free to
download from Microchip® website. The combination of this module and a PIC
microcontroller operating the TCP/IP stack will result in supporting the IEEE
802.11 and IP services, which allows for an immediate implementation of a
wireless web server. The microcontroller communicates through the application
programming interface (API) command which is within the TCP/IP stack.