Project Wisdom StoneNetworking using MiWi

Done By: Amnon Balanov & Yosef SolomonSupervisor: Boaz MizrachiProject ID: d02310

Small sensors, with very low power consumption

Planted under roads Performing monitoring of road maintenance

status

Project Wisdom Stone

THIS INFORMATION WILL SAVE MONEY BY DECREASING MAINTENANCE COSTS AND TIME!

Based on a PIC24 micro-processor

Networking (two alternatives):o 2.4 GHz enabled by a MRF24J40 IEEE 802.15.4 Tx/Rx.o 433 MHz enabled by a MRF49XA Tx/Rx.

Networking will run MiWi (Microchip propriatory S/W stack)

***All components are made by Microchip.

Project Wisdom Stone

The design and implementation of a networking S/W stack who’s functions will be:

1. Transmissions of aquired data to a PC via similar unit

2. Parsing commands received from PC station

3. WAKE interrupts from sleep - for sensing sessions

Project Goals

Tx/Rx◦ Communications with the PC unit

microSD memory chip◦ Stores aquired data

PIC interrupts◦ Wake/Transmission interrupts

System I/O

Extra BoardPICtailEvaluation Board – Explorer

16

MicroCTRL - PIC24FJ256GB11

0

General HW Scheme

Sensor Array

NetworkingMRFJ40MB

ORMRF49XA

MEM- Flash & SRAM

MEM- microSD

SPISPI

SPI

Internal flash Program Memory- 256kB◦ Current tests show 10% usage

SRAM Data Memory- 16kB◦ Current tests show 10% usage◦ We will have a double buffer, a block length each,

for communications (block=1kB; currently) 3 SPI Ports

◦ We will use one for the MRF & one for the µSD.

PIC-24FJ256GB110

MRFJ40MBUses 2.4GHz RFUses O-QPSK modulation.Receiver FIFO- 144 byte, interrupts when a

whole packet was received.Transmitter FIFO- 128 byte.Packet header length ~20 Bytes (TBD)Power: 19-23 mA Working

~2 µA Sleeping

Uses 433MHz RF Uses FSK modulation. Receiver FIFO- 16 bit, interrupts when full

up to a certain point (configurable). Transmitter Registers- two 1-byte Registers,

similar use to the PIC double buffer. Packet header length ~10 Bytes (TBD) Power: 11-15 mA Working

0.3 µA Sleeping

MRF49XA

MRF24J40◦ 250 kbps transmission speed

MRF49XA◦ 115.2 kbps digital transmission speed◦ 256 kbps analog transmission speed

PIC24FJ256GB110◦ computational power of 16 MIPS◦ sampling rate of 500 ksps

microSD◦ reads and writes are in the MB/s range

System Speeds

General Software Layers Diagram

Definition and support the following working modes:◦ Store samples (SS): Samples are stored in non-volatile

memory for long period. ◦ Transmit samples (TS): Samples are read and

transmitted from non-volatile memory through Wireless/UART/USB.

◦ Online sample and transmit (OST): Samples are read from sensor and then transmitted through UART/USB/Wireless, using internal SRAM memory (double buffer mechanism), without access to non-volatile memory.

Sample / Transmit working modes

The device is activated using a well defined CLI (Command Line Interface).

The command line strings are received from either:◦ TXRX wireless port◦ USB port◦ UART port◦ Internal ROM table (Configuration table)

Each command will be executed, and a prompt prefix, followed by the command result, will be returned to the command origin source (TXRX, USB or UART).

CLI Commands

We will write a parser converting the different commands to a short field divided command.

Work on the parser is in its early stages. For example:

◦ eeprom <sub command> <optional parameters>◦ |5 bit command code| |3 bit sub-command| |8-bit optional|

CLI Commands Parsing

As was decided, we use the MiWi SW Stack.◦ MiWi is a proprietary stack designed by

Microchip, free to use. The stack is implemented as general as

possible and suits to the proposed HW networking modules.

We use the MiWi P2P protocol.

MiWi SW Stack

The MiWi Protocol is divided into two parts:◦MiApp - upper level used to connect our

application with the MiWi P2P protocol 

◦MiMAC - Using the MiMAC layer, we can easily switch between different RF transceivers such as MRF24J40 and MRF49XA.

MiWi Protocol (Cont.)

MiWi Protocol Layers

This layer will give 5 major interfaces:◦ Initialization- allows configuration of selected

hardware.◦ Hand-shaking-allows discovering and

connecting to peers and network.◦ Receiving- allows receiving information over the

air.◦ Transmitting- allows sending information over

the air.◦ Extended Functionality- allows environment

noise and power saving control.

MiApp Layer

The MiMAC Layer allows us the abstraction of the Transceiver driver- we use it regardless of the driver used (at least in theory)

Mainly implements the MiApp API

MiMAC Layer

Configuration File

Allows the easy configuration of the whole

application:

Switching between Transceivers

Enabling/Disabling different functions of the SW

stack

Further Development- Allows choosing the Protocol

TXInit()◦ Initialize network parameters.◦ The sensor creates a network.

TXBatchInit()◦ Initialize a new batch.

TXBlock()◦ Transmits block of size 1KB.

TXStop()◦ Ends transmission.

TXRXDeviceTasks()◦ This function will take care of the transceiver periodic

tasks (handle TX and RX tasks).

TXRX Commands- Main Loop API

Network Diagram

INIT INIT

Send Command

Interpret command & Send Data

Go To Sleep

Receive Data

New/End Session

The sensor side PC side

In order to comply with time constraints of other parts of the WiStone we will test to see how big a payload we can use.

In case we see a packet’s transmission cannot be interrupted and in order to allow easy coordination, we will make the transmission of a packet atomic (non-preemptive).

Coordination in the WiStone

The two Transceivers support a sleep mode. They save the current status on

configuration registers to allow easy wake up.

The only way to wake up the transcievers is through pre-programmed timers on the transceivers or the PIC.

We need to figure out how to allow access not at a pre-determined time.

Sleep

Finishing software development & basic testing (3 weeks)- ◦ Completing code for:

The Main Loop functions.

Writing and documenting the parser (1 week)

Outdoors Testing (1 week)-Testing the network capabilities under simulated conditions.

Wrap-Up (1-2 weeks)-◦ End of term presentation◦ End of Project Report*

Est. Total: 6-7 weeks.*Might be delayed because of Exam period

Estimated Schedule