YellowJacket Arduino with WiShield Wifi (Part 2)

YellowJacket Hardware Details — 

The YellowJacket (YJ) Wifi board is composed of two primary components: 1) an Arduino Uno-equivalent microprocessor board; and, 2) a Microchip MRF24WB0MA wifi backpack. A considerable amount of time was spent tracing connections between the two boards to understand the hardware design. Following is a fairly in-depth report on the hardware.

• YJ board contains the Atmel Mega328P-AU AVR which serves as Arduino UNO.
• YJ board uses KA7805R to convert RAW (7-24V) to 5v.
• YJ board uses ST-L1117-33 to convert ~5v to 3.33v @ 800ma.
• YJ Vin = RAW > 5v, VCC = 5v.
• YJ 16 mhz resonator.
• YJ Red LED 5V Power on indicator.
• MRF24 pin 23 ==> YJ pin 10; SPI CS for MRF24.
• YJ Pin 13 Green LED indicator next to Reset push button.
• YJ Pin 9 Green LED indicator next to pins 12-13, set on/off in WiServer software
• FTDI programming ports on end of board to USB/FTDI pins (Gnd, Gnd, 5V, TX, RX, DTR/Reset)
  • or, can be connected to external Shield pins (Gnd, Gnd, 5V, RX(D0), TX(D1), Reset)
• Microchip MRF24WB0MA Wifi
• 802.11b Wireless (WLAN) Wifi 11 Mbps, 2.4 Ghz band.

YJ Arduino UNO-equivalent Features

• ATMega328 microprocessor running at 16MHz with external resonator
• Uses FTDI cable for Arduino programming
• Supports auto-reset
• Raw DC input 7V up to 16V
• 5V regulator to VCC and VOUT
• 3.3V regulator (max 800ma)
• Over current protected
• On board red Power and 2 green Status LEDs
• Analog Pins: 6
• Digital I/Os: 14, 0=RX, 1=TX
• No on-board USB port.
• No on-board memory card connections.
• WiShield original code does not support DNS; must use IP addresses.
• No UART level shifting due to on board direct connections to Arduino.

ATMega328 Microprocessor Features

• Atmel 8-bit AVR
• Absolute maximum VCC: 6V
• Maximum current for chip: 200mA
• Maximum current per pin: 40mA
• Recommended current per pin: 20mA
• Flash Program Memory: 32kB
• EEPROM: 1kB
• Internal SRAM 2kB
• ADC: 10-bit
• PWM: 8bit

YellowJacket Microchip MRF24WBOMA Wifi Module

The Microchip MRF24WB0MA Wifi (aka MRF24) module is installed as a backpack on the YellowJacket breakout board to provide wifi capability on an Arduino UNO platform (aka YJ Arduino). A YellowJacket circuit diagram was requested and received from Rugged Circuits (non-disclosure agreement). JTAG (N/C) pins are for testing circuit boards and are not used in Arduino applications.

Note:

• YJ Arduino pin D1 is High when MRF24 is active. Blinks low on signal activity.
• YJ Arduino pin D2 <=> MRF24 INT0 pin blinks low on wifi activity. Do not use pin D2 in apps.
• YJ Arduino pin D8 is MRF24 hibernate. Do not use pin D8 in apps.
• YJ Arduino pin D9 is used by WiServer software to indicate MRF24 is active.
• YJ Arduino pin D10 is MRF24 SPI CS pin. Do not use pin D10 in apps.
• YJ Arduino pins D11, D12, and D13 are SPI pins. Use in apps for SPI control.
• YJ Arduino pin Vin == pin RAW (+7-12VDC). Pin RAW provides power to => KA7805R which outputs 5V to => L1117 which outputs 3V3.

MRF24WB0MA Circuit Design and Pinouts

 The MRF24WB0MA backpack module is a 3.3V surface mount 36 pin device with integrated wifi antenna. The YJ Arduino is a 5V device which provides 3.3V for the wifi module.

Reference: http://ww1.microchip.com/downloads/en/DeviceDoc/70632C.pdf

Typical circuits with the MRF24WB0MA use a few pull-up and pull-down resistors and filtering capacitors for power conditioning and to interface to an external microprocessor board.

The MRF24WB0MA module uses SPI pins CS, SDO, SDI, and SCK, plus INT to communicate with an external microprocessor.

MRF24 Pin Connections

MRF24 Pin ==> Visible Connection on YellowJacket Board

01 ==> Gnd

04 ==> TCK to MRF24 pin 16 both pulled high to +3V3

07 ==> Reset normally high, asynchronous hardware reset when pin=low for the MRF24 module

10 ==> Gnd

16 ==> Write protect (this pin is used to enable FLASH update) to MRF24 pin 04 Write-protect for the internal module SPI Flash.

17 ==> VDD3V3

18 ==> Gnd

19 ==> Gnd

20 ==> ‘Hibernate’  CE connected to YJ Arduino pin D8; Hibernate mode enable (high input will disable the module)

23 ==> SPI CS connected to YJ Arduino pin D10 CS

25 ==> Gnd

26 ==> Serial debug port input (Connected on board?)

27 ==> Serial debug port output  (Connected on board?)

28 ==> Gnd

29 ==> +VDD 3.3V

30 ==> Gnd

32 ==> SPI SDO Data Out to YJ Arduino pin D12 MISO

33 ==> Interrupt Out connected to YJ Arduino hardware interrupt pin D2; (active low interrupt indicator pin (~INT), which is asserted low by the MRF24 when data is available for the host device. The ~INT line is de-asserted high after the data transfer is complete.)

34 ==> SPI SCK Clock Input to YJ Arduino pin D13 CLK

35 ==> SPI SDI Data In to YJ Arduino pin D11 MOSI

36 ==> Gnd

(Feb 20, 2016)