scicoslab and canopen - supsi

CAN SCICOS CAN200 Example

ScicosLab and CANopen

Ing. Roberto Bucher

Scuola Universitaria Professionale della Svizzera Italiana (SUPSI)

Manno - July 1. 2009


Objectives

See how CANopen devices can be integrated in a Scicos blockdiagram

Learn how to implement new CANopen devices

Introduce the CAN200 interface dongle


Outline

1 CAN and CANopen

2 Scicos and CANopen

3 The CAN200 card

4 Example


CAN

Controller Area Network

Controller area network (CAN or CAN-bus) is a vehicle busstandard designed to allow microcontrollers and devices tocommunicate with each other within a vehicle without a hostcomputer.

It was designed specifically for automotive applications but isnow also used in other areas.

Development of the CAN-bus started originally in 1983 atRobert Bosch GmbH.


CAN

Interface


CANopen

CANopen

CANopen is a communication protocol and device profilespecification for embedded systems used in automation.

In terms of the OSI model, CANopen implements the layersabove and including the network layer.

The lower level protocol implementing the data link andphysical layers is usually Controller Area Network (CAN).


Device model

Device model

Every CANopen device must implement:

A Communication unit (protocol for messaging)

A state machine (Initialization, Pre-operational, Operational,Stopped)

An object dictionary used for configuration and non-realtimecommunication with the device.

The application part


Communication objects

Communication objects


Protocol

Network management (NMT) protocol

The NMT protocols are used to issue state machine changecommands (ie. to start and stop the devices), detect remote devicebootups and error conditions.


Protocol

Service Data Object (SDO) protocol

The SDO protocol is used to set and read values from the objectdirectory of a remote device.


Protocol

SDO

Master (PC) CAN dev 1 CAN dev 2

CMD

ACK

DATA

REQ

CMD

ACK

REQ

DATA


Protocol

Process Data Object (PDO) protocol

Process Data Object protocol is used to process real time dataamong various nodes.

Synchronous

On change

TX and RX PDO’s

More values in the same message


Protocol

PDO

ENCODER CURRENT SPEED


Protocol

PDO

Master (PC) CAN dev 1 CAN dev 2

SYNC

SYNC

SYNC

SYNC

PDO’s

PDO’s

PDO’s

PDO’s


Protocol

Others

Synchronization Object (SYNC) protocol

Time Stamp Object (TIME) protocol

Emergency Object (EMCY) protocol


Integration in Scicos

Integration in Scicos

device

CANopen

Initialization

CAN

device

CANopen

Initialization

CAN

device

Receive

CANopen

Thread


The “canopen.c” file

canopen.c

Initializes the RTDM driver

Contains a function to register the TX PDO

Starts a high priority thread for receiving the CAN messages

Handles TX PDO1 and TX PDO2, but can be easy extendedto handle more PDO’s



canopen.c

The canopen.c file



PDO handling

.....

127 for TX PDO1

.....

127 for TX PDO2

.....

127 for TX PDO1

.....

127 for TX PDO2


The “canopen sync” file

The “canopen sync.c” file

Simply sends a SYNC (0x80) message to all CANopen devices

All the devices handle the SYNC message as follow:

Devices with configured TX PDO’s send the requested valuesto the masterDevices with configured RX PDO’s set the last received value


Reading PDO’s

Reading from the CAN Bus

A real-time thread scheduled with SCHED FIFO and priority“1” is responsible to get the messages from the CAN bus.

The receiving procedure runs using the interrupt of the CANbus RTDM driver.

The registered PDO’s are saved into the two PDO matrices.

8 procedures allow to extract the values from the PDOmessages (1,2,4 bytes, signed, unsigned)


The palette

Additional palettes

out.txtsignal means

01sINIT ENC

0x3782Pport_out

0x37815Pport_in

10Switch

0x08encoderEpos

0x08motor IEpos

10x08Epos Analog

synccanopenEpos

0x08motXEpos


Implementing a new block

The interface

1

gain_x

00.01sINIT ENC

11 11

11

synccanopenEpos

0x08encoderEpos

0x08motor IEpos


Implementing a new block

The implementation

The Implementation file


The card

The CAN200 dongle


The card

Details

based on the SJA1000 chip

Little modifications on the original CAN200 board

16 Mhz quarzScmhitt trigger chip instead of a nand

Quite simple

PCB and scheme are provided


Hardware

The CAN200 dongle - Scheme

6/23/2009 15:45:44 /home/bucher/eagle/can200/can200.sch (Sheet: 1/1)

+

1

23

IC1A

4

56

IC1B

9108

IC1C

12

1311

IC1D

1 62 73 84 95

X111421531641751861972082192210231124122513

X2

VCC

3

GND

2

TXD1RS8

RXD4

VREFOUT5

CANH 7

CANL 6

AD023

AD124

AD225

AD326

AD427

AD528

AD61

AD72

ALE/AS3

CS4

RD/E5

WR6

CLK_OUT7

MODE11

INT16

XTAL1 9

XTAL2 10

VDD1 22

VSS1 8

VDD3 12

VSS3 15

TX0 13

TX1 14

RX0 19

RX1 20

VSS2 21

VDD2 18

RESET 17

21

Q1

X4-1

X4-2

R1

R3

R2

C3

C1

C2

C4

R4

1

JP12

R5

C6

LED1

R6

74HC132

74HC132

74HC132

74HC132

8MHz

GNDGND

VCC

VCC

VCC

GND

47k

270

10k

100n

33p

33p

220p

470

GND

120

47uF

470


Software

The Driver

RTDM driver

Modified peaks dongle driver

Few lines changed


Example

The Servo motor


Example

Features

Motor Output

Hall sensor+Incremental encoder

2 Analog inputs −10V ÷ +10V

1 Analog output 0V ÷ 10V

10 Digital inputs

5 Digital outputs


Example

Motor equations

Differential equation

Jm · ϕ̈m = −Dm · ϕ̇m + Kt · I

In Laplace

Φ(s) =KtJm

s2 + DmJm

· s· I (s)


Example

Motor equations

Φ(s) =KtJm

s2 + DmJm

· s· I (s)

can be rewritten as

Φ(s) =K

s2 + α · s· I (s)

where

K =Kt

Jm, α =

Dm

Jm


Example

Motor equations

With I (s) as step signal we obtain:

Φ(s) =K

s2 + α · s· I0

s

that in time domain becomes

ϕ(t) = −K · I0α2

+K · I0α

· t +K · I0α2

· eα·t


Example

Example

Controller

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