PEAK-Flash
User Interface Help

# Select Bit Rate Dialog Box

To be able to use PEAK-Flash to flash a hardware that is connected via a CAN bus, the correct bit rate of the CAN bus must be selected in addition to the CAN interface that is to be used for communication. This is done with the help of the Select Bit Rate dialog box.

To access the Select Bit Rate dialog box, choose the Modules connected to the CAN-Bus option on the Select Hardware page, and then click on the Change button.

Mode

Depending on the PCAN hardware used, different operating modes are available for the hardware. For older PCAN hardware that is not compatible with CAN FD, only the CAN (SJA1000) mode is available. For newer PCAN hardware compatible with CAN FD, in addition to a more comfortable CAN mode the CAN FD mode can be used.

When a PCAN net is selected in the list of available PCAN hardware and PCAN nets, all parameters for the connection are determined by the net definition, so that none of the drop-down lists and input fields on the CAN Setup tab can be changed.

Mode | Description
CAN (SJA1000) | Configures a PCAN hardware by selecting the two values for the bus timing registers BTR0 and BTR1 of the SJA1000 CAN controller for the CAN 2.0B protocol. The bus timing always refers to a clock frequency of 8 MHz. This mode can also be used with newer CAN-FD-compatible PCAN hardware that are not based on the SJA1000 CAN controller. Since the controller of a CAN-FD-compatible hardware only allows clock frequencies of 20 MHz or higher, the bit rate parameters are converted accordingly in order to obtain the desired bit timing.
CAN | Configures a PCAN hardware to use the CAN 2.0B protocol.
CAN FD | Configures a PCAN hardware to use the CAN FD protocol.

## CAN (SJA1000) Mode

After selecting the CAN (SJA1000) mode the following selection and input fields are available:

Clock Frequency

The bit timing for SJA1000 bit rates is always calculated based on 8 MHz, so the clock frequency cannot be changed in this mode.

Database Entry

Enables a quick selection of one of the bit rates that are stored in the database. Predefined bit rates are marked with a yellow star , and user-specific bit rates with a user symbol .

(Manage Bit rates)

Use this button to display a dialog window where you can create your own bit rates or customize the predefined ones.

Bit Rate

Here you can enter the bit rate in kbit/s that you want to use. If the exact bit rate is not possible, a corresponding message is displayed when you leave the field and the next possible bit rate is suggested.

Bus Timing Register 0

Allows the direct editing of the value for the BTR0 register of the SJA1000 CAN controller. For more information about the Bus Timing Register 0, refer to the Philips SJA1000 Stand-alone CAN controller data sheet, chapter 6.5.1.

Bus Timing Register 1

Allows the direct editing of the value for the BTR1 register of the SJA1000 CAN controller. For more information about the Bus Timing Register 1, refer to the Philips SJA1000 Stand-alone CAN controller data sheet, chapter 6.5.2.

Prescaler

This field informs about the current prescaler value (1-64), which is extracted from Bits 0 to 5 from the Bus Timing Register 0.

Sample Count

Allows you to select either 1 or 3 samples, which determines the value of the SAM bit in the BTR1 register. For more information, refer to the Philips SJA1000 Stand-alone CAN controller data sheet, chapter 6.5.2.1.

(Parameter Table)

The table in the lower area of the dialog window shows all possible combinations of BTR0 and BTR1 that lead to the desired bit rate and result in a sample point of at least 50%.

## CAN Mode

After selecting the CAN mode the following selection and input fields are available:

Clock Frequency

Allows the selection of one of the clock frequencies 20, 24, 30, 40, 60, and 80 MHz, which is to serve as the basis for calculating the bit timing of the CAN bus.

Database Entry

Enables a quick selection of one of the bit rates that are stored in the database. Predefined bit rates are marked with a yellow star , and user-specific bit rates with a user symbol .

(Manage Bit rates)

Use this button to display a dialog window where you can create your own bit rates or customize the predefined ones.

Bit Rate

Here you can enter the bit rate in kbit/s that you want to use. If the exact bit rate is not possible, a corresponding message is displayed when you leave the field and the next possible bit rate is suggested.

Sample Point

Here you can enter the desired sample point in percent. If the exact sample point is not possible, a corresponding message is displayed when the field is exited and the next possible sample point is suggested.

(Bit Timing Configuration)

Opens a dialog window that offers various parameter combinations to match the selected bit rate, which lead to the same bit rate but may result in different sample points.

(Copy Parameters to Clipboard)

Copies the parameters of the currently selected bit rate as text to the Clipboard.

Prescaler

This field informs about the prescaler value (1-1024) of the currently selected bit rate.

## CAN FD Mode

After selecting the CAN FD mode the following selection and input fields are available:

Clock Frequency

Allows the selection of one of the clock frequencies 20, 24, 30, 40, 60, and 80 MHz, which is to serve as the basis for calculating the bit timing of the CAN bus.

Bit Rate Preset

Enables a quick selection of one of the bit rate presets that are stored in the database. Predefined bit rate presets are marked with a yellow star , and user-specific presets with a user symbol .

(Manage Bit rates)

Use this button to display a dialog window where you can create your own bit rates and presets or customize the predefined ones.

### Nominal Bit Rate

This group offers settings for the nominal part of a CAN FD bit rate.

Database Entry

Enables a quick selection of one of the nominal bit rates that are stored in the database. Predefined bit rates are marked with a yellow star , and user-specific bit rates with a user symbol .

Bit Rate

Here you can enter the nominal bit rate in kbit/s that you want to use. If the exact bit rate is not possible, a corresponding message is displayed when you leave the field and the next possible bit rate is suggested.

Sample Point

Here you can enter the desired sample point of the nominal bit rate in percent. If the exact sample point is not possible, a corresponding message is displayed when the field is exited and the next possible sample point is suggested.

(Bit Timing Configuration)

Opens a dialog window that offers various parameter combinations to match the selected nominal bit rate, which lead to the same bit rate but may result in different sample points.

(Copy Parameters to Clipboard)

Copies the parameters of the currently selected nominal and data bit rates as text to the Clipboard.

Prescaler

This field informs about the prescaler value (1-1024) of the currently selected nominal bit rate. Please note that for CAN FD the values of the prescalers for nominal and data bit rate should be identical to ensure trouble-free operation.

### Data Bit Rate

This group offers settings for the data part of a CAN FD bit rate. The bit rate selected is used to transfer the data fields of a CAN FD frame with a higher bit rate. This higher bit rate is applied to those CAN FD frames that have the 'Bit Rate Switch' flag set.

Data Bit Rate

The option to disable the data bit rate settings is present only for downward compatibility reasons.

Disabling the data bit rate results in using the nominal bit rate parameters also for the data bit rate, which is not recommended. Individual nominal bit rate parameter values could lie outside the permitted range of values for the corresponding data bit rate parameters, as a result of which the initialization of the CAN controller will fail.

Database Entry

Enables a quick selection of one of the data bit rates that are stored in the database. Predefined bit rates are marked with a yellow star , and user-specific bit rates with a user symbol .

Bit Rate

Here you can enter the data bit rate in kbit/s that you want to use. If the exact bit rate is not possible, a corresponding message is displayed when you leave the field and the next possible bit rate is suggested.

Sample Point

Here you can enter the desired sample point of the data bit rate in percent. If the exact sample point is not possible, a corresponding message is displayed when the field is exited and the next possible sample point is suggested.

(Bit Timing Configuration)

Opens a dialog window that offers various parameter combinations to match the selected data bit rate, which lead to the same bit rate but may result in different sample points.

(Copy Parameters to Clipboard)

Copies the parameters of the currently selected nominal and data bit rates as text to the Clipboard.

Prescaler

This field informs about the prescaler value (1-1024) of the currently selected data bit rate. Please note that for CAN FD the values of the prescalers for nominal and data bit rate should be identical to ensure trouble-free operation.

See also

Manage Bit Rates Dialog Box

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