1 Hardware Specifications

1.1 Signaling Level/Voltage Ratings

Notes:

• The CAN/I²C Activity Board Pro will not supply target power on the Komodo or Aardvark header.
• The CAN bus is not electrically isolated from the rest of the board.

1.2 CAN Signaling Characteristics

1.2.1 Speed

The CAN/I²C Activity Board Prowill run at 125 kbps by default. If a different bitrate is desired, set the board to auto-baud on the CAN bus through the appropriate selection pin (see Section 2.4).

1.2.2 Known CAN Limitations

CAN Buffer Saturation

The CAN bridge includes multiple receive buffers for CAN packets. If the CAN receive buffer overflows, then packets will be acknowledged by the node, but not processed.

The CAN bridge also includes a small number of transmit buffers for which outgoing packets can be queued. A packet will not leave this queue until it has been successfully transmitted. If the queue is full when the bridge attempts to write another CAN packet to the bus, it will block until there is room in the queue.

In order to avoid either buffer saturating, no more than approximately 10 packets per 100 ms should be sent on the CAN bus.

1.3 I²C Signaling Characteristics

1.3.1 Speed

The I²C on the CAN/I²C Activity Board Pro operates at 100 kHz.

1.3.2 Pull-up Resistors

The CAN/I²C Activity Board Pro includes a 4.7 k pull-up resistor to VDD on the SCL and SDA lines.

1.3.3 Known I²C Limitations

The CAN/I²C Activity Board Pro is not designed to work with multi-master situations. If the board is intended to be used with other I²C masters then the I²C master functionality of the CAN bridge should be inhibited. See Section 2.4 for more information on how to do this.

1.4 Communication Protocol

It is important to understand the basics of how the CAN/I²C Activity Board Pro operates and how the target devices communicate over both CAN and I²C. None of the targets are CAN-compatible themselves, but the CAN/I²C Activity Board Pro features a microcontroller which serves as a bridge between the CAN bus and the target interfaces. This bridge allows all of the targets to operate as CAN nodes on the CAN bus. Many of the targets are I²C devices, so they can interface directly with the Aardvark I²C/SPI Host Adapter. The microcontroller also implements an I²C slave (0x42), which allows the LCD display and ADC to communicate over I²C.

1.4.1 CAN

The CAN bridge simulates a number of CAN nodes by bridging each I²C device on the CAN/I²C Activity Board Pro to the CAN bus. Each node ID is equivalent to the I²C ID which is displayed on the silkscreen of the PCB.

The CAN/I²C Activity Board Pro follows a protocol that is similar to CANOpen. Each 11-bit ID field of the CAN packet is split into a 7-bit node address and a 4-bit opcode. Two opcodes are defined in Table 2 which can be used for standard communication with the CAN bridge.

As an example, if we were to set the programmable LEDs on the board, then we would send the following information on the bus:

On the other hand, if we were to poll the Joystick for its current position, we would send the following information on the bus:

The response from the CAN bridge will then be a non-RTR packet with the same CAN ID, and will have the appropriate data payload.

Using these Standard Opcodes provides a convenient method for getting and setting device data, however it does not necessarily provide a means to access the full functionality of each node. For example, this protocol does not define a method for configuring specific pins of the GPIO port to be inputs or outputs.

In order to complete more advanced tasks on a node, it is important to remember that each node on the CAN/I²C Activity Board Pro is in reality an I²C device, and that the CAN bridge functions as an I²C master on this bus. The opcodes provided earlier simply abstracted one or more I²C calls to the I²C slave in order to get or set the device data. The following opcodes provide a mechanism for controlling the I²C master explicitly. In each case the opcode determines the type of I²C command being sent, the node ID would represent the I²C slave to be addressed, and the data payload would be the actual data transmitted on the bus.

By following the specific I²C communication protocol for a specific sensor, the extended CAN opcodes can be used to access any feature of the I²C device.

As an example, if we were to configure the GPIO port expander to have 4 nputs and 4 outputs, we would need to send the following command:

Once configured this way, the GPIO input pins could be polled or outputs set through the standard opcode method described previously.

If instead we were to read out the current configuration of the GPIO node, we would actually need to send two I²C commands. The first sets up the register we wish to read with a No Stop condition, and the second reads the data out.

Please note that once a No Stop condition is issued to the CAN bridge, it will ignore all standard requests until a Stop condition has been issued. Additionally, if an I²C command is lost due to arbitration issues, it will not be retransmitted on the I²C bus.

1.4.2 I²C

The CAN/I²C Activity Board Pro uses I²C to communicate with each of the nodes on the bus. For specifics on how to communicate with a specific node, please refer to Section 3.

1.5 CAN Bridge Interrupts

The CAN bridge is tied to the interrupt pins of the two port expander targets (See Section 3 ). Thus when one of these pins asserts, the appropriate I²C target will be polled, and the data will be broadcast on the CAN bus.

1.6 Application Notes

1.6.1 CAN Node Errors

The CAN packet transmitted to the CAN/I²C Activity Board Pro must match one of the defined Opcode and RTR schemes defined in Section 1.4.1. If not, then the packet will be ignored by the CAN bridge.

Additionally, the Standard Opcodes will only be recognized for node IDs that are defined in Table 9. The Extended Opcodes can be used with any node ID, and can thus be used to extend to other I²C slaves that are not included on the CAN/I²C Activity Board Pro.

If there is ever an I²C error when the CAN bridge is attempting to process an RTR packet, a response will still be sent by the bridge. However, the DLC will be 0 and the payload will be empty.

1.6.2 I²C Board Configuration

The CAN bridge implements an I²C master in order to talk with the devices on the board. However, the CAN bridge is not designed to work in multi-master situations. In order to successfully use the CAN/I²C Activity Board Pro with an external master (such as the Aardvark I²C/SPI Host Adapter), it is important to configure the board correctly.

To use the board with an I²C master, please configure the board in the following manner:

• Disconnect the board from any CAN bus.
• SEL0 should be left open.
• SEL1 should be left open.
• SEL2 should be jumped.

For more information on the selection pins, please refer to Section 2.4.

 

2 Connectors, Headers, Buttons, and LEDs

2.1 Port Expander Header (J201)

This header allows the port expander to interface with external circuitry. See Section 3.4 for more information.

2.2 Komodo Connector (J301)

This connector is provided to interface with the Komodo CAN Interfaces. It is a male DE-9 connector compatible with the SAE J1939 CAN-CIA standard. The pinout of this connector is shown in Figure 2 and Table 4.

It is necessary to provide target power (4.5V-5.0V) to the CAN/I²C Activity Board Pro through V+ on the Komodo connector, or through VDD on the Aardvark connector.

2.3 CAN Termination Header (J302)

This header can be jumped to connect a 120 Ohm parallel termination resistor to the CAN bus.

2.4 Select Header (J303)

The Selection Header provides a mechanism for changing the behavior of the CAN bridge. These pins are sampled once upon reset. To change the mode, simply place jumpers on the appropriate selection, and hit the reset button.

Notes:

• If SEL0 is selected, the CAN bridge will not process any packets on CAN or I²C until a baudrate has been selected. This can take several seconds.
• SEL1 should never be selected if the CAN/I²C Activity Board Pro is being used in I²C mode, as it can cause multi-master arbitration errors.
• SEL2 should be selected whenever the CAN/I²C Activity Board Pro is being used in I²C mode. This will prevent multi-master arbitration errors when interrupts occur.

2.5 Program Header (J304)

This header must be jumped to program the AT90CAN32 microcontroller.

2.6 Aardvark Connector (J401)

This connector is provided to interface with the Aardvark I²C/SPI Host Adapter. It is necessary to provide target power (4.5 V to 5.0 V) to the CAN/I²C Activity Board Pro through VDD on this connector, or through V+ on the Komodo connector.

This connector's pinout is listed in Table 6.

2.7 ADC Header (J402)

This header includes power, ground, and three analog input pins to the ADC. This connector's pinout is listed in Table 7.

See Section 3.6 for more details about the ADC.

2.8 DAC Header (J403)

This header includes power, ground, and the DAC's analog output. This connector's pinout is listed in Table 8.

See Section 3.1 for more details about the DAC.

2.9 Reset Button (SW301)

This button resets the CAN/I²C Activity Board Pro microcontroller and restores the default configuration of all the peripherals.

2.10 Power LED (D304)

This green LED illuminates when the CAN/I²C Activity Board Pro is powered.

2.11 Activity LED (D305)

This amber LED blinks whenever the CAN/I²C Activity Board Pro is processing a CAN or I²C packet.

 

3 Targets

Table 9 summarizes all the target devices and their CAN IDs/I²C addresses. Each node can be accessed by I²C or CAN. In situations where the Extended CAN Opcodes are used (see Table 3 ), follow the notes on I²C operation for that device.

3.1 DAC (0x09)

Part:

National Semiconductor DAC081C085

Datasheet:

http://www.national.com/profile/snip.cgi/openDS=DAC081C085

This component is a single-channel 8-bit digital-to-analog converter. It can drive its output between 0V and VDD, with a precision of approximately 12.9 mV. It can communicate directly over I²C, or over CAN through the bridge. Please see the DAC081C085 datasheet for more information.

On startup, the DAC's output is set to high-impedance. Once a value is set it will be configured to normal operation, and output the desired voltage.

3.1.1 CAN Operation

Get Sensor Data

Not applicable. This device will not respond to Get Sensor Data requests.

Set Sensor Data

To set the DAC value, a single byte needs to be transmitted with the requested DAC setting. See Table 10.

Example: Setting the DAC to approximately 1.65 V. See Table 11.

3.1.2 I²C Operation

Please consult the DAC081C085 datasheet for details on I²C operation.

3.2 Motion Sensor (0x1D)

Part:

STMicroelectronics LIS33DE

Datasheet:

www.st.com/stonline/products/literature/ds/15596/lis33de.pdf

This component is a 3-axis linear accelerometer. It can communicate directly over I²C or over CAN through the bridge. See the PCB silkscreen for the orientation of X, Y, and Z. Please see the devices datasheet to correlate the digital reading with the physical value.

3.2.1 CAN Operation

Get Sensor Data

The motion sensor will respond with 3 bytes of accelerometer data when a Get Sensor Data request is made. See Table 12.

Getting Sensor Data is equivalent to doing a multi-byte read from the OUT_X register, as described in the device datasheet.

Example: Polling the Motion sensor. See Table 13.

Set Sensor Data

Not applicable. This device will not respond to Set Sensor Data requests.

3.2.2 I²C Operation

Please consult the LIS33DE datasheet for details on I²C operation.

3.3 Light Sensor (0x29)

Part:

Avago Technologies ADPS-9300

Datasheet:

http://www.avagotech.com/docs/AV02-1077EN

This light sensor converts light intensity (irradiance) into a 16-bit digital signal. It can communicate directly over I²C, or over CAN through the bridge. Please see the devices datasheet to correlate the digital reading with the irradiance value.

3.3.1 CAN Operation

Get Sensor Data

The light sensor will respond with 2 bytes of irradiance value within the visible spectrum when the Get Sensor Data request is made. See Table 14.

Getting Sensor Data is equivalent to reading from the Ch0 light sensor, as described in the device datasheet.

Example: Polling the light sensor. See Table 15.

Set Sensor Data

Not applicable. This device will not respond to Set Sensor Data requests.

3.3.2 I²C Operation

Please consult the ADPS-9300 datasheet for details on I²C operation.

3.4 GPIO Port Expander (0x39)

Part:

NXP Semiconductors PCA9554AD

Datasheet:

http://ics.nxp.com/products/pca/datasheet/pca9554.pca9554a.pdf

This is an 8-pin port expander which can be accessed through CAN or I²C. On start-up, all pins are configured as inputs, and can be read over CAN. By communicating directly with the device over I²C, it is possible to configure the pins as outputs. The port expanders pins are connected to a header for easy access, as described in Section 2.1. If interrupts are not disabled, changes to the inputs will cause the bridge to broadcast the data on the CAN bus.

3.4.1 CAN Operation

Get Sensor Data

f

The port expander will respond with 1 byte of data describing the current value of each input pin. See Table 16.

Getting the Sensor data is equivalent to reading from the Input Register, as described in the device datasheet.

Example: Polling the GPIO port expander. See Table 17.

Set Sensor Data

The outputs of the port expander can be set by sending 1 byte of data describing the desired value of each output. See Table 18.

Setting the Sensor Data is equivalent to writing to the Output Register, as described in the device datasheet.

Note that the port expander powers up as all inputs. In order to have outputs configured the Extended Opcodes will have to be used.

Example: Setting every other output high on the GPIO port expander. See Table 19.

3.4.2 I²C Operation

Please consult the PCA9554AD datasheet for details on I²C operation.

3.5 Joystick/LEDs (0x3A)

Parts:

NXP Semiconductors PCA9554AD

Datasheet:

http://ics.nxp.com/products/pca/datasheet/pca9554.pca9554a.pdf

The joystick and LEDs are connected to an NXP PCA9554AD port expander. The microcontroller communicates with the joystick and LEDs through this port expander. The joystick and LED connections to the port expander pinout are listed in Table 20.

This two-axis joystick is a very simple device. It has five output pins (up, down, left, right, and select) which are asserted high when the joystick is moved to that position. These outputs are then connected to an NXP I/O port expander which can communicate the status over CAN and I²C.

There are three active high LEDs controlled by the port expander: D201, D202, and D303. The color of these LEDs are specified in Table 20.

On startup the port expander is configured to have all joystick connections as inputs, and all LED connections as outputs.

3.5.1 CAN Operation

The operation of the Joystick and LEDs is equivalent to that of the GPIO Port Expander (Section 3.4), except that the node ID is 0x3A instead of 0x39.

3.5.2 I²C Operation

Please consult the PCA9554AD datasheet for details on I²C operation. Do not attempt to configure pins IO0-IO4 as outputs, this can damage the CAN/I²C Activity Board Pro.

3.6 ADC/LCD (0x42)

Part:

Internal to CAN Bridge

Datasheet:

N/A

Unlike all the other devices on the board, the ADC and LCD are not external I²C devices. Instead, they are implemented on the MCU, and can be accessed over I²C or CAN at the node address of 0x42.

The CAN Bridge MCU has a built-in ADC which is exposed on the PCB. The CAN/I²C Activity Board Pro allows the user to read 3 of these analog inputs with an 8-bit resolution. Inputs may range from 0 V to a maximum of 3.3 V.

To determine the analog input value from the received ADC data, use the following equation:

The LCD is a 2x8 character display that is connected to the CAN bridge over a parallel bus. The characters on the display are ASCII-encoded.

3.6.1 CAN Operation

Because the ADC and LCD slaves are internal to the CAN bridge, CAN communication will not actually cause any I²C traffic to be transmitted on the bus. Whereas requests to other nodes would cause an appropriate I²C write/read, these nodes are simply handled internally. This is true even when using an Extended Opcode.

Get Sensor Data

The CAN Bridge will respond with 3 bytes of ADC information when the Get Sensor Data request is made. See Table 22.

The Get Sensor Data will only get data from the ADC. It will not return any LCD information.

Example: Polling the ADC. See Table 23.

Set Sensor Data

The Set Sensor Data is used to set the LCD text on the screen. See Table 24.

The Set Sensor Data will only set data on the LCD. It will not set any ADC information.

The LCD screen is broken up into four segments of 4 characters. Each data segment is written to individually. If not all 4 characters of a segment are included in the CAN payload, then the remainder are filled with spaces.

Example: Writing Hello World! to the LCD screen. See Table 25.

3.6.2 I²C Operation

Because both the ADC and LCD share a device address of 0x42, they are individually referenced by a register address. The ADC is at register address 0x01, and the LCD is at register address 0x02.

Setting the ADC Value

This is not applicable. Attempting to set the ADC value will do nothing.

Getting the ADC Value

Getting the ADC Value is a two step process. It requires setting up the proper register address, and then reading back the 3 ADC values. Reading more than 3 bytes will return 0xFF for any additional bytes.

The ADC will respond with 3 bytes of data. See Table 26.

Example: Polling ADC sensor. See Table 27.

Setting the LCD Display

The LCD screen is broken up into four segments of 4 characters. Each data segment can be written to individually.

The LCD segment will also auto-increment and wrap when operated in I²C mode. Therefore if segment 0x00 is selected, and 8 bytes are written, then the entire first line will be configured. No more than 16 character bytes can be written to in a single I²C operation.

See Table 28 for a description of the data payload.

Example: Writing Hello World to the LCD screen. See Table 29.

Getting the LCD Display

Over I²C it is also possible to read out the current LCD setting. Like the ADC this requires two steps. The first step sets up the register we wish to read from as well as the segment to start reading from. Bytes are then read consecutively out.

See Table 30 for a description of the data payload.

Example: Reading data out of LCD screen. See Table 31.

3.7 Temperature Sensor (0x4E)

Part:

Maxim Integrated Products DS75

Datasheet:

http://datasheets.maxim-ic.com/en/ds/DS75.pdf

This temperature sensor provides temperature readings over a range of -55°C to +125°C. It can communicate directly over I²C or over CAN through the bridge.

3.7.1 CAN Operation

To request data from the temperature sensor over CAN, send a remote frame with an ID of 0x4E. A CAN data frame will then be broadcast with one byte of temperature data. On start up this device is configured for 9-bit temperature readings.

Get Sensor Data

The temperature sensor will respond with 2 bytes of temperature data when a Get Sensor Data request is made. See Table 32.

Getting Sensor Data is equivalent to reading from the Temperature Register as described in the device datasheet.

Example: Polling the temperature sensor. See Table 33.

Set Sensor Data

Not applicable. This device will not respond to Set Sensor Data requests.

3.7.2 I²C Operation

Please consult the DS75 datasheet for details on I²C operation.

 

4 References

4.1 Examples

Example scripts which communicate with the target devices on the CAN/I²C Activity Board Pro are available for download on the Total Phase website: http://www.totalphase.com/support/product.

4.2 Technical Specifications

The CAN/I²C Activity Board Pro draws approximately 50 mA of current from the power source, either the Komodo Interface or the Aardvark adapter.

Detailed information about the Technical Specifications of the Komodo CAN Interfaces and the Aardvark I²C/SPI Host Adapter can be found on the Total Phase website: http://www.totalphase.com.

 

5 Legal / Contact

5.1 Disclaimer

All of the software and documentation provided in this datasheet, is copyright Total Phase, Inc. ("Total Phase"). License is granted to the user to freely use and distribute the software and documentation in complete and unaltered form, provided that the purpose is to use or evaluate Total Phase products. Distribution rights do not include public posting or mirroring on Internet websites. Only a link to the Total Phase download area can be provided on such public websites.

Total Phase shall in no event be liable to any party for direct, indirect, special, general, incidental, or consequential damages arising from the use of its site, the software or documentation downloaded from its site, or any derivative works thereof, even if Total Phase or distributors have been advised of the possibility of such damage. The software, its documentation, and any derivative works is provided on an "as-is" basis, and thus comes with absolutely no warranty, either expressed or implied. This disclaimer includes, but is not limited to, implied warranties of merchantability, fitness for any particular purpose, and non-infringement. Total Phase and distributors have no obligation to provide maintenance, support, or updates.

Information in this document is subject to change without notice and should not be construed as a commitment by Total Phase. While the information contained herein is believed to be accurate, Total Phase assumes no responsibility for any errors and/or omissions that may appear in this document.

5.2 Life Support Equipment Policy

Total Phase products are not authorized for use in life support devices or systems. Life support devices or systems include, but are not limited to, surgical implants, medical systems, and other safety-critical systems in which failure of a Total Phase product could cause personal injury or loss of life. Should a Total Phase product be used in such an unauthorized manner, Buyer agrees to indemnify and hold harmless Total Phase, its officers, employees, affiliates, and distributors from any and all claims arising from such use, even if such claim alleges that Total Phase was negligent in the design or manufacture of its product.

5.3 Contact Information

Total Phase can be found on the Internet at http://www.totalphase.com/. If you have support-related questions, please go to the Total Phase website. For sales inquiries, please contact [email protected].

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All rights reserved.