Digilent 410-273P-KIT - Manual (Page 7)

WF32 Reference Manual
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Page 7 of 24
Note that the series resistors that are part of the voltage clamp circuit to provide 5V tolerance on the analog
capable I/O pins, limiting the current that can be sourced or sunk by those pins. These resistors add 200 ohms of
resistance to the input/output circuit and limit the effective drive current to about 1mA-2mA source/sink capability
on the analog capable pins.
Connectors J7 and J9 are 2x8 female pin header connectors that provide digital I/O signals. The outer row of pins
(closer to the board edge) corresponds to the I/O connector pins on an Arduino Uno or Duemilanove board. The
inner row of pins provides access to the extra I/O signals provided by the PIC32 microcontroller.
Connector J8 is a 2x6 female pin header connector that provides access to the analog input pins on the
microcontroller. The outer row of pins corresponds to the six analog pins on an Arduino Uno or Duemilanove. The
inner row of pins is for the additional I/O signals provided by the PIC32 microcontroller. The analog pins on J8 can
also be used as digital I/O pins.
The chipKIT/Arduino system uses logical pin numbers to identify digital I/O pins on the connectors. The logical pin
numbers for the I/O pins on the WF32 are 0-48. These pin numbers are labeled in the silk screen on the board.
Pin numbers 0-13 are the outer row of pins on J9 and J7, from right to left. Pin numbers 14-19 are the outer row of
pins on J8 from left to right. Pins 20-25 are the inner row of pins on J8 from left to right. Pin numbers 26-41 are the
inner row of pins on J9 and J7 from right to left. Pin 42 is the pin labeled A on J7. This pin is normally the reference
voltage for the microcontroller’s A/D converter, but can also be used as a digital I/O pin.
In addition to the connector pin, Pin 13 also connects to the user LED LD3. Pin 43 connects to user LED LD5. Pin 43
does not attach to any connector. Pin 44 is the SS signal for SPI port 2, and discussed more in the SPI section
below. Pins 45 and 46 are intended to be used for I
2 C and are connected to the 2x1 female header connector, J6.
Pins 47 and 48 connect to the user LEDs LD5 and LD6.
The analog inputs on connector J8 are assigned pin numbers. The outer row of pins on J8 is analog inputs A0-A5.
The inner row of pins is A6-A11. These pins are also assigned digital pin numbers; A0-A5 are digital pins 14-19, and
A6-A11 are 20-25.
6 802.11b/g Interface
The 802.11b/g compatible WiFi interface on the WF32 is provided by a Microchip MRF24WG0MA WiFi module.
This module provides the radio transceiver, antenna, and 802.11 compatible network firmware.
The MRF24WG0MA firmware provides the 802.11 network protocol software support. The DNETcK and DWIFIcK
libraries provide the TCP/IP network protocol support that works with the 802.11 protocol support provided by the
WiFi module.
The primary communications interface with the MRF24WG0MA WiFi module is a 4 wire SPI bus. This SPI bus uses
SPI4 in the PIC32 microcontroller, and this SPI controller is dedicated to use for communications with the WiFi
module
The WiFi module supports SPI clock speeds up to 25MHz. In addition to the SPI interface, the interface to the WiFi
module also includes a reset signal, an interrupt signal and a hibernate signal. The active low RESET signal is used
to reset the WiFi module The external interrupt signal, INT, is used by the module to signal to the host
microcontroller that it needs servicing by the microcontroller software. The INT signal on the WiFi module is
connected to external interrupt INT4 on the PIC32 microcontroller. The active low HIBERNATE signal is used to
power the WiFi module down and put it into a low power state.