(01204423) Sensor Node Programming II (UART and Radio) Chaiporn - - PowerPoint PPT Presentation

Network Kernel Architectures and Implementation (01204423) Sensor Node Programming II (UART and Radio)

Chaiporn Jaikaeo chaiporn.j@ku.ac.th Department of Computer Engineering Kasetsart University

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Outline

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UART communication



Single-hop radio communication

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Connecting Mote to PC



USB connector on IWING-MRF and IWING-JN



USB dongles

3.3V 5V RX TX GND

USB Dongle based on Silicon Labs’s CP2102 ThaiEasyElec’s USB Dongle (FDTI)

3.3V RX TX GND

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UA UART RT API (motelib/uart.h)



Enable UART (both TX and RX)

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Send a single byte over UART



Send multiple bytes over UART

uartEnable(true,true); uint8_t buf[10]; : uartWrite(buf, 10); uartWriteByte(50);

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UART API (cont'd)

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Check whether there is any data received from UART

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Read a single byte from UART input buffer



Send formatted string over UART using Standard I/O library

uint8_t byte = uartReadByte(); #include <stdio.h> : : printf("Hello, world\n"); printf("i = %d\n", i); if (uartInputLen() > 0) ...

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Processing UART Data on PC

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Locate UART device file

• Run dmesg to find out
• Usually /dev/ttyUSB0 or /dev/ttyACM0

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For textual data

• Run terminal program such as screen,

gtk-term, putty on UART device



For binary data

• Any UART library can be used
• E.g., Python's serial package

$ dmesg : [70063.712091] usb 4-1: new low speed USB device using uhci_hcd and .. [70063.871042] usb 4-1: config 1 interface 1 altsetting .. [70063.871056] usb 4-1: config 1 interface 1 altsetting .. [70063.895220] cdc_acm 4-1:1.0: ttyACM0: USB ACM device

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USB-UART Implementation



MoteLib provides UART-via-USB implementation for IWING-MRF platform (>= rev. 388)

• Emulated using V-USB library by Objective

Development

• Based on AVR-CDC project

(http://www.recursion.jp/avrcdc/)



Requires no USB dongle



Build your app with UART_VIA_USB=1

$ make UART_VIA_USB=1 ...

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Example: sense-to-uart.c

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Sense light intensity every second; send values to display via UART

#include <stdio.h> #include <motelib/system.h> #include <motelib/timer.h> #include <motelib/uart.h> #include <motelib/sensor.h> #include <motelib/actor.h> Timer t; void senseDone(uint16_t value); void sense(Timer *t); void boot() { uartEnable(true,true); timerCreate(&t); timerStart(&t, TIMER_PERIODIC, 1000, sense); } void senseDone(uint16_t value) { printf("Light = %d\r\n", value); actorSetState(ACTOR_0, 0); } void sense(Timer *t) { actorSetState(ACTOR_0, 1); sensorRequestAnalog(SENSOR_1, senseDone); }

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Testing sense-to-uart

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Build with UART_VIA_USB option



Capture UART output using screen (or gtk-term or putty)

$ make UART_VIA_USB=1 flash $ screen /dev/ttyACM0

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Radio Communication

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IWING-MRF: Microchip's MRF24J40 controller

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IWING-JN: Built-in

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IEEE 802.15.4 @ 2.4 GHz, 250 kbps

• 16 non-overlapping channels
• 16-bit node ID
• 16-bit PAN (Personal Area Network) ID

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Configuring Radio (IWING-MRF)



Use config-mote.py script located in $MOTELIB_DIR/platforms/iwing- mrf/tools



Have mote enter bootloader, then run:

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E.g., set address to 234 and PAN ID to 555

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Set channel to 0x1A

$ cd $MOTELIB_DIR/platforms/iwing-mrf/tools $ ./config-mote.py $ ./config-mote.py --address 234 --panid 555 $ ./config-mote.py --channel 0x1A

Configure Radio (IWING-JN)



Set the following variables via make

• DEFAULT_ADDR
• DEFAULT_PANID
• DEFAULT_CHANNEL



Example:

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$ make PLATFORM=iwing-jn DEFAULT_ADDR=50

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Radio Message Format

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Type and application data are provided by the application via Radio API

Type (1 byte) 802.15.4 Header Seq No. (1 byte) App Data (max ~100 bytes) Check sum

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Radio API (motelib/radio.h)



Broadcast a message (type=7) containing "HELLO" to all neighbors

• Call txDone() when message has been sent
• Use NULL when callback is not needed

radioRequestTx(BROADCAST_ADDR, 7, "HELLO", 5, txDone); : void txDone(RadioStatus status) { : } radioRequestTx(BROADCAST_ADDR, 7, "HELLO", 5, NULL);

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Radio API (cont'd)

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Set a handler to process received messages

radioSetRxHandler(receive); : void receive(Address src, MessageType type, void *msg, uint8_t len) { : }

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Example: sense-to-base.c

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Every second, each sensor node measures light intensity and reports to the base station

• Assume base station has address = 0

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Base station reports light measurements over UART

Base station Sensor nodes measuring light intensity Sensor node

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sense-to-base.c

void sense(Timer *t) { actorSetState(ACTOR_0, 1); sensorRequestAnalog( SENSOR_1, senseDone); } void senseDone(uint16_t value) { radioRequestTx(0, 1, &value, sizeof(value), NULL); actorSetState(ACTOR_0, 0); } #include <motelib/system.h> #include <motelib/timer.h> #include <motelib/radio.h> #include <motelib/sensor.h> #include <motelib/actor.h> Timer t; void sense(Timer *t); void senseDone(uint16_t value); void boot() { timerCreate(&t); timerStart( &t, TIMER_PERIODIC, 1000, sense); }

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base.c

#include <stdio.h> #include <motelib/system.h> #include <motelib/radio.h> #include <motelib/uart.h> void receive(Address src, MessageType type, void *msg, uint8_t len) { if (type == 1) { printf("Node %d: Light = %d\n", src, *((uint16_t*)msg)); } } void boot() { uartEnable(true,true); radioSetRxHandler(receive); }

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Exercise: Voting Machine



Create an application for wireless voting machine

• Allow user to cast a vote using the USER button
• Voting choices are: Red (1), Yellow (2),

Green (3), or No Vote (0)

• When the USER button is pressed,
• Set LED status accordingly
• Report current vote to the base station (#1) with

message type 50