The Stacker is an XBee radio-sized Arduino-compatible microcontroller that can be “stacked” directly underneath the radio. It is intended for use with devices that already use the XBee’s 20-pin footprint. Future designs could easily utilize other microcontrollers or host sensors. The goal is to create plug-and-play tools for prototyping new concepts that extend the popular radio’s feature set. A few iterations have created a prototype that works well, supports USB programming, wireless programming, I2C, SPI, digital and analog I/O!
XBee Stacker 2
This is the next iteration of an Arduino-compatible board the size of an XBee that fits right underneath the radio. It uses the ATMega32U4 so in Arduino you can program it as a Leonardo board.
Features
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I2C
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SPI
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scriptable interruption of:
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all UART transactions
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XBee pin sleep controls
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local support for:
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association indicator
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commissioning button
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17 total digital i/o pins (14 Arduino, 4 XBee)
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6 configurable as ADC analog inputs
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4 configurable as PWM analog outputs
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2 attachable interrupts
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USB serial programming
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wireless programming
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EEPROM
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multiple UARTs
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Use of all Arduino libraries, e.g. servo, stepper, displays, capacitive sensing, rfid, sd cards etc.
Pinouts
Bottom of XBee Stacker 2:
| Physical Pin | Function | Arduino Connection |
| 1 | Power supply | VCC |
| 2 | Arduino software TX | D11 (softserial TX) |
| 3 | Arduino software RX, PWM | D10 (softserial RX) |
| 4 | MISO (spi), digital i/o | MISO (spi) |
| 5 | input for Arduino reset | RESET |
| 6 | digital i/o, analog output | D9 |
| 7 | MOSI (spi), analog input, digital i/o | MOSI (spi) |
| 8 | analog input, digital i/o | D8/A8 |
| 9 | PWM, interrupt, digital i/o | D7 |
| 10 | GND | GND |
| 11 | SCK (spi), digital i/o | SCK (spi) |
| 12 | SDA (i2c) interrupt, digital i/o | D2/SDA (i2c) |
| 13 | SCL (i2c), interrupt, PWM, digital i/o | D3/SCL (i2c) |
| 14 | analog input, digital i/o | D4/A6 |
| 15 | PWM, digital i/o | D5 pwm |
| 16 | analog input, PWM, digital i/o | D6/A7 pwm |
| 17 | analog input, digital i/o | A3 |
| 18 | analog input, digital i/o | A2 |
| 19 | analog input, digital i/o | A1 |
| 20 | analog input, digital i/o | A0 |
Top of XBee Stacker 2
| XBee Physical Pin | Function | XBee Connection |
| 1 | Power supply | VCC |
| 2 | Arduino RX | D0 RX |
| 3 | Arduino TX | D1 TX |
| 4 | – | – |
| 5 | – | - |
| 6 | – | – |
| 7 | – | – |
| 8 | – | |
| 9 | control for pin sleep | D12 |
| 10 | GND | GND |
| 11 | – | – |
| 12 | CTS | A4 |
| 13 | – | – |
| 14 | voltage reference | VCC |
| 15 | association output | <led> |
| 16 | RTS | A5 |
| 17 | Arduino Reset (p1) via cap. | <capacitor> for reset |
| 18 | - | – |
| 19 | - | – |
| 20 | – | – |
Schematics & Board Layout
XBee Stacker Arduino 2.0-board
XBee Stacker Arduino 2.0-schematic
Code
Program as an Arduino Leonardo board!
Licensing
Not determined, leaning toward open source hardware.