Download CAN-USB-Micro Hardware Manual - esd electronics, Inc.

CAN-USB/Micro 

Small CAN USB Interface 

in DSUB9 Enclosure 

Manual 

to Product C.2068.02 

CAN-USB/Micro Manual • Doc. No.: C.2068.21 / Rev. 1.1 Page 1 of 36 

esd electronic system design gmbh 

Vahrenwalder Str. 207 • 30165 Hannover • Germany 

http://www.esd.eu • Fax: 0511/37 29 8-68 

Phone: 0511/37 29 80 • International: +49-5 11-37 29 80

N O T E 

The information in this document has been carefully checked and is believed to be entirely reliable. 

esd makes no warranty of any kind with regard to the material in this document, and assumes no 

responsibility for any errors that may appear in this document. esd reserves the right to make 

changes without notice to this, or any of its products, to improve reliability, performance or design. 

esd assumes no responsibility for the use of any circuitry other than circuitry which is part of a 

product of esd gmbh. 

esd does not convey to the purchaser of the product described herein any license under the patent 

rights of esd gmbh nor the rights of others. 

Trademark Notices 

esd electronic system design gmbh 

Vahrenwalder Str. 207 

30165 Hannover 

Germany 

Phone: +49-511-372 98-0 

Fax: +49-511-372 98-68 

E-Mail: info@esd.eu 

Internet: www.esd.eu 

USA / Canada: 

esd electronics Inc. 

525 Bernardston Road 

Suite 1 

Greenfield, MA 01301 

USA 

Phone: +1-800-732-8006 

Fax: +1-800-732-8093 

E-mail: us-sales@esd-electronics.com 

Internet: www.esd-electronics.us 

CANopen® and CiA® are registered community trademarks of CAN in Automation e.V. 

USB is a registered trademark of the Universal Serial Bus Implementers Forum, INC. 

Windows is a registered trademark of Microsoft Corporation in the United States and other countries. 

All other trademarks, product names, company names or company logos used in this manual are reserved by their 

respective owners. 

Page 2 of 36 Manual • Doc. No.: C.2068.21 / Rev. 1.1 CAN-USB/Micro

Document file: 

Date of print: 2011-06-06 

Hardware version: 1.1 

Firmware version: Since version 1.15 

Document History 

I:\Texte\Doku\MANUALS\CAN\CAN-USB-Micro\CAN-USB-Micro_Manual_en_11.odt 

The changes in the document listed below affect changes in the hardware as well as changes in 

the description of the facts, only. 

Revision Chapter Changes versus previous version Date 

1.0 - First version 2011-01-28 

1.1 

5.4, 12. Notes on software driver support inserted. 2011-06-01 

7. 

8. 

Documentation corrected: CAN interface is not 

electrically isolated. Editorial revision of the chapter. 

CAN transceiver test revised. Editorial revision of the 

chapter. 

2011-06-01 

2011-06-01 

12. Order information moved to chapter 12. 2011-06-01 

Technical details are subject to change without further notice. 

CAN-USB/Micro Manual • Doc. No.: C.2068.21 / Rev. 1.1 Page 3 of 36

Safety Instructions 

! When working with CAN-USB/Micro follow the instructions below and read the manual carefully to protect 

yourself and the CAN-USB/Micro from damage. 

The esd guarantee does not cover damages which result from improper use or disregard of safety 

instructions and warnings. 

! Protect the CAN-USB/Micro from dust, moisture and steam. 

! Protect the CAN-USB/Micro against shocks and vibrations. 

! The CAN-USB/Micro may become warm during normal use. Always allow adequate ventilation around 

the CAN-USB/Micro and use care when handling. 

! Do not operate the CAN-USB/Micro adjacent to heat sources and do not expose it to unnecessary 

thermal radiation. Ensure an ambient temperature as specified in the technical data. 

! Do not use damaged or defective cables to connect the CAN-USB/Micro and follow the CAN wiring hints 

in chapter: "Correctly Wiring of CAN Networks". 

Qualified Personal 

This documentation is directed exclusively towards qualified personal in control and automation engineering. 

The installation and commissioning of the product may only be carried out by qualified personal, which is 

authorized to put devices, systems and electric circuits into operation according to the applicable national 

standards of safety engineering. 

Conformity 

The CAN-USB/Micro meets the demands of the EU regulations and EMC standards printed in the conformity 

declaration at the end of this manual. 

Intended Use 

The intended use of the CAN-USB/Micro is the operation as a CAN-USB interface. 

The esd guarantee does not cover damages which result from improper use, usage not in accordance with 

regulations or disregard of safety instructions and warnings. 

! The operation of the CAN-USB/Micro in hazardous areas, or areas exposed to potentially explosive 

materials is not permitted. 

! The operation of the CAN-USB/Micro for medical purposes is prohibited. 

Service Note 

The CAN-USB/Micro does not contain any parts that require maintenance by the user. The CAN-USB/Micro 

does not require any manual configuration of the hardware. Unauthorized intervention in the device voids 

warranty claims. 

Disposal 

Devices which have become defective in the long run have to be disposed in an appropriate way or have to 

be returned to the manufacturer for proper disposal. Please, make a contribution to environmental protection. 


Table of contents 

1. Overview......................................................................................................................................6 

1.1 Module Description................................................................................................................6 

2. View of the Connectors................................................................................................................7 

3. Hardware Installation....................................................................................................................8 

4. LED Description...........................................................................................................................9 

5. Summary of Technical Data.......................................................................................................10 

5.1 General Technical Data.......................................................................................................10 

5.2 USB Interface .....................................................................................................................10 

5.3 CAN Interface......................................................................................................................10 

5.4 Software Support.................................................................................................................11 

5.5 Firmware License.................................................................................................................11 

6. Connector Assignment...............................................................................................................12 

6.1 USB.....................................................................................................................................12 

6.2 CAN ....................................................................................................................................13 

7. Correctly Wiring of CAN Networks..............................................................................................14 

7.1 General Rules......................................................................................................................14 

7.2 Cabling................................................................................................................................15 

7.3 Termination..........................................................................................................................15 

7.4 Earthing...............................................................................................................................16 

7.5 Bus Length...........................................................................................................................16 

7.6 Examples for CAN Cables...................................................................................................17 

8. CAN-Bus Troubleshooting Guide...............................................................................................18 

8.1 Termination..........................................................................................................................18 

8.2 Ground.................................................................................................................................19 

8.3 Short Circuit in CAN Wiring..................................................................................................19 

8.4 CAN_H/CAN_L-Voltage ......................................................................................................19 

8.5 CAN Transceiver Resistance Test ......................................................................................20 

9. Software.....................................................................................................................................21 

9.1 Installation and Configuration under Windows XP...............................................................21 

10. Appendix..................................................................................................................................25 

11. Declaration of Conformity.........................................................................................................35 

12. Order Information.....................................................................................................................36 


Overview 

1. Overview 

1.1 Module Description 

C 

A 

N 

B 

U 

S 

DSUB9 Enclosure 

DSUB9 

Male Contacts 

CiA ® Pin Assignment 

Physical 

CAN Layer 

ISO11898-2 

LED 

green 

LED 

red 

Power 

Supply 

3.3 V 

CAN Microcontroller 

USB PWR 

USB Data 

1.0 m USB Cable 

Figure 1: Block-circuit diagram of the CAN-USB/Micro 

The CAN-USB/Micro is a very small, low cost CAN-USB interface for PCs, that fits into a DSUB9 

enclosure. The ARM Cortex-M3 micro controller controls the CAN data. The non isolated CAN 

interface is powered by USB. 

The CAN-USB/Micro supports the USB 2.0 full-speed interface with data rates up to 12 MBit/s. 

USB Type A 

Connector 

Serial line CAN interface (SLCAN) is used as the firmware interface. 

A Windows driver (NTCAN-API), with the usage limited to one application at a time, is available for 

Windows XP/ Vista / 7 (32/64 Bit). 

A Windows driver with full featured NTCAN-API support is available as an option. 

For Linux operating systems the CAN-USB/Micro is fully supported by the SocketCAN project and 

the SLCAN device driver, that is part of recent Linux kernels. 


2. View of the Connectors 

Figure 2: Connectors of CAN-USB/Micro 

View of the Connectors 


Hardware Installation 

3. Hardware Installation 

 

Procedure: 

Read the safety instructions at the beginning of this document carefully, 

before you start with the hardware installation! 

1. Connect the USB connector of the CAN-USB/Micro to the USB bus of the PC. 

2. Connect the 9-pin male DSUB connector to the CAN bus. 

Please remember that the CAN bus has to be terminated at both ends. esd offers 

T-connectors and terminators. Additionally, the CAN-GND-signal has to be grounded at 

exactly one point in the CAN network. Therefore the CAN termination connectors have got a 

grounding contact. A CAN device whose CAN interface is not electrically isolated (like the 

CAN-USB/Micro) corresponds to the grounding of the CAN-GND. 

3. End of hardware installation. 

4. The software installation is described exemplary in the chapter 'Installation and Configuration 

under Windows XP' on page 21. 


4. LED Description 

Figure 3: LEDs CAN-USB/Micro 

Name Colour Description 

Activity green 

CAN-Error red 

on 

USB module is enumerated (a node address is 

assigned to the USB module) 

flash off receives CAN telegrams or USB commands 

off not working 

on 

CAN-Bus-off, 

CAN-Error-passive or 

CAN-Controller-Warn 

off CAN bus OK, (CAN-Error-active) 

LED Description 

LED- 

Description in 

Schematics 

Diagram 

LED102 

LED103 


Summary of Technical Data 

5. Summary of Technical Data 

5.1 General Technical Data 

Temperature range 0...50°C ambient temperature 

Humidity 90% non-condensing 

Power supply via USB: 

nominal voltage: 

current consumption 

(without CAN traffic): 

5 V +5 % /-12% 

typical at 5 V : 50 mA 

Connectors USB - USB 2.0 interface (USB type A plug, X100) 

CAN - CAN interface (9-pin DSUB, male connector, X200) 

Dimensions cable length 1 m including connectors, 

DSUB9: 35 mm x 15 mm x 45 mm 

IP rating IP20 

Weight approx. 100 g 

5.2 USB Interface 

Number 1x USB 

Controller integrated in ARM-Cortex-M3 STM32F105, 32-bit, 72 MHz 

USB interface USB 2.0, Full-Speed, 12 Mbit/s 

Connector USB type A plug 

5.3 CAN Interface 

Number of CAN 

interfaces 

1x integrated in DSUB9-enclosure 

CAN controller integrated in ARM-Cortex-M3 STM32F105, 32 bit, 72 MHz 

CAN protocol ISO 11898-1 

Physical Layer 

Electrical isolation none 

CAN High speed interface according to ISO 11898-2, 

bit rate up to 1 Mbit/s 

Bus termination has to be set externally 

Connector DSUB9, according to DS-303-1 


5.4 Software Support 

Summary of Technical Data 

The CAN-USB/Micro runs with the standard USB-serial system drivers of common operating 

systems. 

A Windows driver (NTCAN-API), with the usage limited to one application at a time for Windows 

XP / Vista / 7 (32/64 Bit) and esd's CAN Tools are in the scope of delivery. 

5.5 Firmware License 

As firmware the CAN-USB/Micro uses the open-source operating system FreeRTOS 

(www.freertos.org). 

The source code of the operating system is published in terms of the GNU Public License (GPL). 

The full text of the license is printed in the document '3rd party licensor notice.pdf' as part of the 

product's documentation. You can contact esd for the complete FreeRTOS source code for the 

CAN-USB/Micro. 


Connector Assignment 

6. Connector Assignment 

6.1 USB 

Device connector: USB connector type A 

Signal Description: 

VBUS... +5 V power supply voltage 

D+, D-... USB signal lines Data+, Data- 

GND... Reference potential 

Pin Position: 

Pin Assignment: 

Pin Signal 

1 

1 2 3 4 

V BUS 

2 D- 

3 D+ 

4 GND 


6.2 CAN 

Device connector: 9-pin DSUB connector, male 

Signal Description: 

Pin Position: 

Pin Assignment: 

Signal Pin Signal 

reserved 1 

CAN_L 2 

CAN_GND 3 

reserved 4 

CAN_GND 

(CAN_Shield) 

CAN_L, CAN_H CAN signal lines 

1 2 3 4 5 

6 7 8 9 

5 

6 reserved 

7 CAN_H 

8 reserved 

9 reserved 

CAN_GND reference potential of local CAN physical layer 

reserved reserved for future applications, do not connect! 

Connector Assignment 


Correctly Wiring of CAN Networks 

7. Correctly Wiring of CAN Networks 

For the CAN wiring all applicable rules and regulations (EC, DIN), e.g. regarding electromagnetic 

compatibility, security distances, cable cross-section or material, have to be met. 

7.1 General Rules 

The following general rules for the CAN wiring must be followed: 

1 A cable type with a wave impedance of about 120 Ω ±10% with an adequate wire cross-section (0.22 

mm²) has to be used. The voltage drop over the wire has to be considered! 

2 Connect 

• 

• 

the two twisted wires to the data signals (CAN_H, CAN_L) and 

the cable shield to the reference potential (CAN_GND)! 

3 The reference potential CAN_GND has to be connected to the functional earth (FE) at exactly one 

point. 

The CAN-USB/Micro connects CAN_GND and FE, so no further connection should be made! 

4 A CAN net must not branch (exception: short cable stubs) and has to be terminated with the 

characteristic impedance of the line (generally 120 Ω ±10%) at both ends (between the signals 

CAN_L and CAN_H and not at GND)! 

5 Keep cable stubs as short as possible (l < 0.3 m)! 

6 Select a working combination of bit rate and cable length. 

7 Keep away cables from disturbing sources. If this cannot be avoided, double shielded wires are 

recommended. 

CAN_H 

CAN_L 

Wire Layout 


Single shielded 

twisted pair cable 

(two-wire cable, 

1x 2x 0.22mm²) 

120 Ohm 

Signal assignment of single shielded twisted pair cable 

with earth and termination 

CAN wire with connectors 

DSUB9 connector 

DSUB9 connector 

(female or male) 

(female or male) 

pin designation 

CAN_GND (at wire shield) 

pin designation 

1 

2 

n.c. 


n.c. 1 

2 

3 

3 

4 n.c. 

n.c. 4 

5 n.c. 

n.c. 5 

6 

7 

n.c. 


n.c. 6 

7 

8 n.c. 

n.c. 8 

9 n.c. 

n.c. 9 

connector case n.c. 

n.c. = not connected 

n.c. connector case 

Figure. 4: CAN wiring with single shielded twisted pair cables 


Page 14 of 36 Manual • Doc. No.: C.2068.21 / Rev. 1.1 CAN-USB/Micro 

120 Ohm 

earth (FE)

7.2 Cabling 


● For devices which have only one CAN connector per net use T-connector and stub (shorter 

than 0.3 m) (available as accessory). 

Figure. 5: Example for proper wiring with single shielded single twisted pair wires 

7.3 Termination 

● Use external termination plugs, because they can be rediscovered more easily than internal 

terminations within the CAN devices! 

● 9-pin DSUB-termination connectors with male and female contacts and earth terminal are 

available as accessories. 



7.4 Earthing 

● CAN_GND has to be connected to the functional earth potential (FE) at exactly one point 

of the network! 

● Each CAN interface without electrically isolated interface like the CAN-USB/Micro acts as 

an earthing point. For this reason do not connect more than one CAN device without 

electrically isolated CAN interface! 

● Earthing can e.g. be made at a connector. 

7.5 Bus Length 

● esd modules typically reach a wire length of 37 m at 1 Mbit/s within a closed net without 

impedance disturbances like e.g. cable stubs >> 0.3 m. 

Bit rate 

[Kbits/s] 

1000 

800 

666.6 

500 

333.3 

250 

166 

125 

100 

66.6 

50 

33.3 

20 

12.5 

10 

Typical values of reachable 

wire length with esd 

interface l max [m] 

37 

59 

80 

130 

180 

270 

420 

570 

710 

1000 

1400 

2000 

3600 

5400 

7300 

CiA recommendations 

(07/95) for reachable wire 

lengths l min [m] 

25 

50 

- 

100 

- 

250 

- 

500 

650 

- 

1000 

- 

2500 

- 

5000 

Table 1: Recommended cable lengths at typical bit rates (with esd-CAN interfaces) 

Note: 

Please note the recommendations according to ISO 11898 for the selection of the cross 

section of the wire depending of the wire length. 


7.6 Examples for CAN Cables 

Manufacturer Type of wire 

U.I. LAPP GmbH 

Schulze-Delitzsch-Straße 25 

70565 Stuttgart 

Germany 

www.lappkabel.de 

ConCab GmbH 

Äußerer Eichwald 

74535 Mainhardt 

Germany 

www.concab.de 


e.g. 

UNITRONIC ®-BUS CAN UL/CSA (1x 2x 0.22) 

(UL/CSA approved) Part No.: 2170260 

UNITRONIC ®-BUS-FD P CAN UL/CSA (1x 2x 0.25) 

(UL/CSA approved) Part No.: 2170272 

e. g. 

BUS-PVC-C (1x 2x 0,22 mm²) Order No.: 93 022 016 (UL appr.) 

BUS-Schleppflex-PUR-C (1x 2x 0,25 mm²) Order No.: 94 025 016 (UL appr.) 

Note: 

Configured CAN cables can be ordered from esd. 


CAN-Bus Troubleshooting Guide 

8. CAN-Bus Troubleshooting Guide 

The CAN Troubleshooting Guide is a guide to find and eliminate the most frequent hardware-error 

causes in the wiring of CAN-networks. 

1 


120 

120 



 


8.1 Termination 

Figure. 6: Simplified diagram of a CAN network 

The termination is used to match impedance of a node to the impedance of the transmission line 

being used. When impedance is mismatched, the transmitted signal is not completely absorbed by 

the load and a portion is reflected back into the transmission line. If the source, transmission line 

and load impedance are equal these reflections are eliminated. This test measures the series 

resistance of the CAN data pair conductors and the attached terminating resistors. 

To test it, please 

1. Turn off all power supplies of the attached CAN nodes. 

2. Measure the DC resistance between CAN_H and CAN_L at the ends of 

the network 1 (see figure above) and at the centre of the network (if the network cable 

consists of more than one line section). 

The measured value should be between 50 Ω and 70 Ω. The measured value should be nearly the 

same at each point of the network. 

If the value is below 50 Ω, please make sure that: 

- there is no short circuit between CAN_H and CAN_L wiring 

- there are not more than two terminating resistors 

- the nodes do not have faulty transceivers. 



2 3 

If the value is higher than 70 Ω, please make sure that: 

- there are no open circuits in CAN_H or CAN_L wiring 

- your bus system has two terminating resistors (one at each end) and that they are 120 Ω 

each. 


V 

V 

1

8.2 Ground 


The CAN_GND of the CAN network has to be connected to the functional earth potential (FE) at 

only one point. This test will indicate if the CAN_GND is grounded in several places. 

To test it, please 

1. 

2. 

3. 

Disconnect the CAN_GND from the 

earth potential (FE). 

Measure the DC resistance 

between CAN_GND and earth 

potential (see figure on the right). 

Connect CAN_GND to earth potential. 

Figure. 7: Simplified schematic diagram of ground test measurement 

The resistance should be higher than 1 MΩ. If it is lower, please search for additional grounding of 

the CAN_GND wires. 

8.3 Short Circuit in CAN Wiring 

A CAN bus might possibly still be able to transmit data if there is a short circuit between CAN_GND 

and CAN_L, but the error rate will increase strongly. Make sure that there is no short circuit 

between CAN_GND and CAN_L! 

8.4 CAN_H/CAN_L-Voltage 

Each node contains a CAN transceiver that outputs differential signals. When the network 

communication is idle the CAN_H and CAN_L voltages are approximately 2.5 volts. Faulty 

transceivers can cause the idle voltages to vary and disrupt network communication. 

To test for faulty transceivers, please 

1. Turn on all supplies. 

2. Stop all network communication. 

3. Measure the DC voltage between CAN_H and GND 

(see figure above). 

4. Measure the DC voltage between CAN_L and GND 

(see figure above). 

functional earth 

(FE) 

CAN-USB/Micro Manual • Doc. No.: C.2068.21 / Rev. 1.1 Page 19 of 36 

3 

2 




 

>1M


Normally the voltage should be between 2.0 V and 4.0 V. 

If it is lower than 2.0 V or higher than 4.0 V, it is possible that one or more nodes have faulty 

transceivers. For a voltage lower than 2.0 V please check CAN_H and CAN_L conductors for 

continuity. For a voltage higher than 4.0 V, please check for excessive voltage. 

To find the node with a faulty transceiver please test the CAN transceiver resistance (see next 

page). 

8.5 CAN Transceiver Resistance Test 

CAN transceivers have one circuit that controls CAN_H and another circuit that controls CAN_L. 

Experience has shown that electrical damage to one or both of the circuits may increase the 

leakage current in these circuits. 

To measure the current leakage through the CAN circuits, please use an resistance measuring 

device and: 

1. Switch off the node and disconnect it from the network 

(see figure below). 

2. Measure the DC resistance between CAN_H and CAN_GND 


3. Measure the DC resistance between CAN_L and CAN_GND 


The measured resistance has to be about 500 kΩ for each signal. If it is much lower, the CAN 

transceiver it is probably faulty. 

Another sign for a faulty transceiver is a very high deviation between the two measured input 

resistance (>> 200%). 

CAN-node 

CAN- 

Transceiver 




Power 

4 

Disconnect 

Power ! 

Figure. 8: Measuring the internal resistance of CAN transceivers 


4 

5 6 

Ω 

Ω 

5 

6 

4 

Disconnect 

CAN !

9. Software 

Software 

Firmware: Seen from the USB, the CAN-USB/Micro implements an USB CDC-ACM 1 device. Thus 

for the operation with Linux and MS Windows systems there is no driver required. CAN data are 

transmitted via SLCAN protocol. 

After connecting the CAN-USB/Micro, the installation of the driver is made via the device manager. 

The installation under Windows XP is described in the following chapter. 

9.1 Installation and Configuration under Windows XP 

Connect the CAN-USB/Micro to a free USB port of the PC. 

Subsequent to that the assistant shows this dialogue in which an adequate driver for Windows is 

searched, select not via Windows Update. 

Configure to install the software from a list or specific location in the following dialogue. 

1 CDC-ACM Control Device Class Abstract Control Model 


Software 

Specify the path of the CAN-USB/Micro drivers in this dialogue. 

Depending on the configuration of the system the following warning can occur. 

Ignore the warning and continue with the installation by clicking Continue Anyway. 


The software is installed. 

Click Finish to close the Wizard after successful installation. 

Software 

The successful configuration can be verified in the device manager. The COM port assigned by 

Windows can vary for different systems. 


Software 

Finally the COM Port has to be assigned to a logical CAN net number. 

This is done by means of the configuration program cancpl. The program can be called via the 

command line or via the dialogue, which opens after pressing Win+R. 

At an installation on a x64-version of Windows, the program is filed in the SysWOW64 directory, 

which is usually not in the search path! 

For further information about how to proceed, please refer to the manual: "CAN-API Part 1: 

Function Description". 

The usage of the driver is limited to one application at a time. 


10. Appendix 

Appendix 

For usage without the MS Windows driver or the Linux-SLCAN-driver, the CAN-USB/Micro can be 

controlled by a terminal tool (e.g. PC) using simple ASCII commands. 

Note: 

This chapter only applies, if MS Windows driver or the Linux-SLCAN-driver are not 

installed. 

We recommend to use the MS Windows driver or the Linux-SLCAN-driver! 

The commands consist of one character for command identification and a command-specific 

number of data bytes. 

... A command must always end with a carriage return (ASCII code 13) 

... is returned, if an error is detected (ASCII code 7) 

The CAN-USB/Micro has two operational modes (the SLCAN- and the esd-mode) and the reset 

mode. To switch from either operational modes to the reset mode, the command C is used. For the 

other way, there are four commands depending on the operational mode and normal CAN-traffic or 

listen-only mode. With the O-command the CAN-USB/Micro switches to normal SLCAN operational 

mode, the L-command is for listen-only SLCAN operational mode, where no CAN-frames can be 

sent. The non-standard o-command switches to the esd operational mode and l to listen-only esd 

operational mode. 

In the SLCAN-mode, every command is acknowledged immediately with a . If timestamps 

are activated with command Z, received CAN-frames show an additional timestamp as a 16-bit 

counter value counting in milliseconds from 0 to 59999 (EA5Fh) and starting at 0 again. 

In the esd-mode, every command is acknowledged immediately with a , except for the 

commands t, T, r and R. Here the comes after the corresponding CAN-frame has been 

sent successfully. In the esd-mode there is a timestamp counter in each received CAN-frame. This 

timestamp has 32 bit, counting microseconds starting from the o or l command. 

When the counter wraps around after 4294967295 (FFFFFFFFh) microseconds, a 

z00000000 is sent on the virtual serial port of the CAN-USB/Micro. In this way, the 

absolute time for each CAN-frame from starting the device can be determined. 


Appendix 

Device 

Control 

Command 

C 

F 

Description Return 

- switches the CAN controller from operational to reset 

mode. The controller then does no longer participate 

in bus activities. 

This command is only active, if the controller is in 

operational mode (switched by command O or o or L 

or l before) 

- reads the error flags from the CAN controller 

Bit 0 Not used 


Bit 2 Error warning 

Bit 3 Data overrun 


Bit 5 Error passive 


Bit 7 Bus error 

A bus error indication can be cleared by command C 

and command command O or o. 

 

or , if not switched by 

command O or o or L or l 

Fxx 

xx... one byte hexadecimal 

with error flags 

Example: Input: F Return: F04 Error warning is set 

- reads the register content from STM32F105 CAN 

controller 

- expects a 12-bit address and returns a 32-bit value 

Gxxx xxx ... register to read (000h-FFFh) 

L 

l 

Gdddd dddd 

dddd dddd ... data in 

register 

or , if xxx is invalid 

Example: Input: G004 Return: G00000C02 

Reset value of CAN_MSR register. See manual of STM32F105 

- switches the CAN controller in listen only mode. 

A channel open command (O or o) is not required 

after command L. To return to reset mode use 

command C to close the channel. 

For reinitialization of the CAN controller send 

command s or S to set the bit rate. 

- switches the CAN controller in esd listen-only mode: 

Received messages are transmitted with 32-bit 

timestamp (circular, base 1 µs). 

In case of overflow of the timestamp a 

"z00000000" is transmitted. 

For further information about listen-only mode see 

command L 

 

or , if bit rate is not set 

 

or , if bit rate is not set 


The Acceptance Code Registers CAN_FxR1 and the Acceptance Mask Registers CAN_FxR2 

define the acceptance filter. 

In the acceptance code registers the bit patterns of messages to be received are defined. 

Appendix 

The bits 3 to 31 contain the bit numbers for Std-IDs (11bit) or Ext-IDs (29bit). Bit 2 contains a fixed 

'0' (for Std-IDs) or '1' (for Ext-IDs). Bit 1 is the filter for the RTR bit in the CAN telegram and bit 0 is 

always '0'. 

x... It is allowed to define certain bit positions as 'don't care' by the corresponding acceptance 

mask registers. 

Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 

Std.-ID 10 9 8 7 6 5 4 3 2 1 0 x x x x x 

Ext.-ID 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 

Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 

Std.-ID x x x x x x x x x x x x x 0 RTR 0 

Ext.-ID 12 11 10 9 8 7 6 5 4 3 2 1 0 1 RTR 0 

For further information about CAN_FxR1 and CAN_FxR2 usage see the data sheet of the 

STM32F105 CAN controller. 

Device Control 

Command 

Mxxxxxxxx 

mxxxxxxxx 


M: Acceptance ID 

- sets acceptance code register of the CAN 

controller. 

For this command the controller has to be in reset 

mode and has to be set-up with command s or S. 

xxxxxxxx ... acceptance code (hex), 

After power-up the default value to 

receive all frames is: 0000 0000h. 

m: Acceptance Mask: 0 = don't care, 

1 = must match 

- sets acceptance mask register of the CAN 

controller. This command works only if controller is 

in reset mode and is set-up with command s or S. 

xxxxxxxx ... acceptance mask [hex] 

After power-up the default value 

to receive all frames is: 0000 0000h. 

 

or , if xxx is 

invalid 

 

or , if xxx is 

invalid 

Example: Input: M24600000 Return: 

mFFE00004 Return: 

only 11-bit identifier 123h will be received 


Appendix 


Command 

N 

O 

o 

riiiL 

RiiiiiiiiL 

 


- reads serial number from CAN-USB-Micro 

The format of the serial number (command N): 

lsss: l... second character of batch 

(GA = 0, GB = 1, ... GP = F) 

sss... serial number in hexadecimal 

e.g.: serial number GB000564 -> 1234h 

- switches the CAN controller from reset into 

operational mode. 

The controller then participates in bus activities. 

The bit rate has to be set by command s or S 

before. 

- opens the CAN controller in esd mode: 

When transmitting, the carriage return is not sent 

until the CAN frame has been transmitted 

successfully. 

In case of bus errors a is transmitted with 

1 second time-out. Additionally received messages 

are transmitted with 32-bit timestamp (circular, base 

1 µs). 

In case of overflow of the timestamp 

z00000000 is transmitted. 

For further information about the open command 

see command O. 

- transmits a standard remote 11-bit CAN frame. 

The controller has to be in operational mode after 

command O or o were sent. 

iii ... identifier [hex] (000h-7FFh) 

L ... data length code (0-8) 

Nlsss 

lsss... serial number 

[hex] 

 

or , if bit rate is 

not set or command 

O, o, L or l were 

already sent before 

 

or , if bit rate is 

not set or command 

O, o, L or l were 

already sent before 

 

or , if identifier is 

invalid 

No CAN data is sent. 

Example: Input: r1234 Return: 

A remote frame with the 11-bit identifier 123h and a data 

length code of 4 without data will be sent. 

- transmits an extended remote 29-bit CAN frame. 



iiiiiiii ...identifier [hex] 

(0000 0000h-1FFF FFFFh) 


 


invalid 

No CAN data is sent. 

Example: Input: R123456780 Return: 

A remote frame with the 29-bit identifier 12345678h and a 

data length code of 0 without data will be sent. 



Command 

Sn 

sxxxxxxxx 


- sets the CAN controller to a predefined standard 

bit rate. 

The CAN controller has to be in reset mode after 

power up or command C. 

The following bit rates are available: 

S0 10 Kbit/s S5 250 Kbit/s 



S3 100 Kbit/s S8 1 Mbit/s 

S4 125 Kbit/s S9 95.238 Kbit/s 

Sa 8.333 Kbit/s Sb 47.619 Kbit/s 

Sc 33.333 Kbit/s Sd 5 Kbit/s 

Example: Input: S8 Return: 

The bit rate is set to 1 Mbit/s, if in reset mode 

- sets user defined values for the bit rate register 

CAN_BTR of the CAN controller 

xxxx xxxx... value [hex] of CAN_BTR 

(0000 0000h - FFFF FFFFh) 

sets the CAN_BTR register according to STM32register 

format. 

Clock rate is 36 MHz. For the prescaler the implicit 

+1 is already considered, i.e. 2 is a prescaler of 2. 

Bit 31 30 

29- 

26 

25- 

24 

23 

22- 

20 

19- 

16 

15- 

10 

9-0 

Meaning SILM LBKM res. SJW res. TS2 TS1 res. BRP 

CAN_BTR register: 

SILM... Silent mode (listen-only) 

LBKM... Loopback mode 

SJW... Synchronization jump width 

TS2... Time segment 2 

TS1... Time segment 1 

BRP... Baud rate prescaler 

Please refer to the STM32F105 CAN controller 

documentation for further information. 

Example: Input: s00D20002 Return: 

The bit rate is set to 1 Mbit/s with SJW = 2, 

Sample Point = 77,8% 

Appendix 

 


invalid 

 

or , if 

xxxx xxxx is invalid 


Appendix 


Command 

tiiiLDDDDDDDD 

DDDDDDDD 

TiiiiiiiiL 

DDDDDDDD 

DDDDDDDD 

V 

v 


- transmits a standard 11-bit CAN frame. 



iii ... identifier [hex] (000h-7FFh) 


DD - DDDDDDDDDDDDDDDD... 

data byte value [hex] (00-FF). 

One to eight data byte values 

Number of given data bytes will be checked 

against given data length code. 

 

or , if 

- identifier is invalid or 

- data is invalid or 

- insufficient amount of 

data bytes or 

- command O or o 

were not sent 

Example: Input: t123499887766 Return: 

A data frame with the 11-bit identifier 123h and the 4 data 

bytes 99h, 88h, 77h and 66h will be sent. 

- transmits an extended 29-bit CAN frame. 



iiiiiiii ...identifier [hex] 

(0000 0000h - 1FFFF FFFFh) 


DD - DDDDDDDDDDDDDDDD... 

data byte value [hex] (00h - FFh). 

One to eight data byte values 

Number of given data bytes will be checked 

against given data length code. 

 

or , if 

- identifier is invalid or 

- data is invalid or 

- insufficient amount of 

data bytes or 

- command O or o 

were not sent 

Example: Input: T1234567829988 Return: 

A data frame with the 29-bit identifier 12345678h and the 

2 data bytes 99h and 88h will be sent. 

-reads hardware and firmware version of the CAN- 

USB/Micro 

Example: Input: V Return: V1011 

Hardware version 1.0, firmware version 1.1x, 

for x see command v. 

- reads detailed firmware version of the CAN- 

USB/Micro 

Example: Input: v Return: v0115 

Firmware version 1.15 

Vhhff 

hh ... hardware 

version [hex] 

ff... firmware version 

[hex] 

vmami 

ma ... major version 

number 

mi... minor 

version number 



Command 

Wrrrdddddddd 

 

Z 

z 

Appendix 

Attention: 

The command W may only be used by qualified personnel with detailed 

knowledge of the CAN controller and the CAN bus! 

Faulty programming may impair or destabilize the correct operation of your system. 

The esd guarantee does not cover damages which result from incorrect 

programming. 


- write internal STM32F105 CAN controller register 

with data, a 12-bit address and a 32-bit value are 

expected 

rrr... register number [hex] (000h - FFFh) 

dddddddd... data [hex] (000000000h - FFFFFFFFh) 

 

or , if rrr is 

invalid 

Example: Input: W01400038F7F Return: 

enables all interrupts in CAN_IER, 

see manual of STM32F105 

- enables or disables the timestamping for receiving 

frames. By default timestamping is disabled. 

If timestamping is enabled, an incoming frame 

includes a timestamp in milliseconds. The 4 

additional characters at the end of the frame contain 

the timestamp, which starts from 0000h and 

overflows at EA5Fh (59999 ms). 

Each increment indicates 1ms within the 60000ms 

frame. 

Turning on the timestamping, the timestamp counter 

will be reset and starts counting from 0000h again. 

- reads the current esd-32-bit timestamp 

(circular, base 1µs), only after after command l or 

o were sent. 

Zssssssss 

ssssssss... timestamp 

in µs 


Appendix 

Receiving CAN Messages: 

If an incoming CAN frame has been received successfully, it will be transmitted via USB in the 

following formats: 

The first ASCII character (t, T, r, R) indicates the type of the received CAN telegram. 

11-bit ID frame 

tiiiLDDDDDDDDDDDDDDDD[ssss|ssss] 

11-bit ID Remote frame 

riiiL[ssss|ssss] 

29-bit ID frame 

TiiiiiiiiLDDDDDDDDDDDDDDDD[ssss|ssss] 

29-bit ID Remote frame 

RiiiiiiiiL[ssss|ssss] 

Description: 

r... identifier of remote 11-bit frame 

R... identifier of remote 29-bit frame 

t... identifier of 11-bit frame 

T... identifier of 29-bit frame 

iii / iiiiiiii... 

ID bytes (000h - 7FFh) or (0000 0000h - 1FFF FFFFh) 

L... data length code (0-8) 

DD - DDDDDDDD DDDDDDDD... 

one to 8 data bytes (00h - FFFF FFFF FFFF FFFFh), the length is variable and 

depends on the number of available data bytes. 

Always an even number of charactrs is transmitted. 

ssss... optional timestamp (0000h - EA5Fh) [hex] in SLCAN format after input of Z 

ssssssss... optional timestamp (0000 0000h - FFFF FFFFh) [hex] in esd format in µs, 

after input of o or l. 


Further Examples: 

SLCAN-Mode 

Input Return Meaning 

S8 sets baud rate to 1Mbit/s 

O initialises CAN-Interface in SLCAN-mode 

Z switches on SLCAN timestamps 

t12329988 

- r23404711 

esd-Mode 

Input Return Meaning 

Appendix 

sends a CAN-frame on identifier 123h with 2 data 

bytes 99h , 88h 

a remote frame on identifier 234h with data length 

code 0 has been received 18193 (4711h ) 

milliseconds after command Z 

S4 sets baud rate to 125kbit/s 

o initialises CAN-interface in esd-mode 

t12329988 

- r234001159A68 

- z00000000 

send a CAN-frame on identifier 123h with 2 data 

bytes 99h , 88h , the returning comes after 

the frame has been successfully sent 

a remote frame on identifier 234h with data length 

code 0 has been received 18193000 (1159A68h ) 

microseconds after command o 

4294967296 (100000000h ) microseconds have 

been elapsed since command o or l 


Appendix 

The following table gives an overview about the command status depending on the controller mode 

Description: 

x ... enabled 

- ... disabled 

Command 

Operational Mode 

channel open 

Reset Mode 

channel closed 

C x - 

F x - 

G x x 

L - x 

l - x 

M - x 

m - x 

N x x 

O - x 

o - x 

r x - 

R x - 

S - x 

s - x 

t x - 

T x - 

V x x 

v x x 

W x x 

Z x x 

z x x 


11. Declaration of Conformity 

Declaration of Conformity 


Order Information 

12. Order Information 

Type Description Order No. 

CAN- USB/Micro 

Manuals: 

Intelligent CAN interface in DSUB9-format, including 1 m 

USB data cable with USB type-A connector, 

incl. Windows driver and CAN Tools 

C.2068.02 

CAN-USB/Micro-ME Hardware manual in English C.2068.21 

Table 2: Order information

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