PEAK-Flash
User Interface Help

# Manage Bit Rates Dialog Box

With the help of the Manage Bit rate dialog box you can inspect the individual parameters of the predefined bit rates, and you can define your own bit rates and compose bit rate presets for CAN FD. Bit rate presets are combinations of nominal and data bit rates that can be selected in the Bit Rate Selection dialog box to determine a CAN FD bit rate as simply as possible.

To access the Manage Bit rates dialog box, click on the button in the Select Bit Rate dialog box.

Predefined elements in the various lists are marked with the icon , and user-defined elements with the icon .

To rename user-defined elements in the lists, click with the mouse in the list on the name of the element to enable the edit mode, or press the [F2] key when a list has the input focus.

The bit rates are divided into 3 categories, which can be selected via tabs.

Tab | Description
CAN (SJA1000) | Configures bit rates that can be used with PCAN hardware that is equipped with an SJA1000 CAN controller for the CAN 2.0B protocol. The bit timing here always refers to a clock frequency of 8 MHz.
CAN | Configures bit rates for the CAN 2.0B protocol that can be used with PCAN hardware that supports bit timing based on clock frequencies greater than 8 MHz. Such PCAN hardware is usually also compatible with the CAN FD protocol.
CAN FD | Configures bit rates that are used with the CAN FD protocol. CAN FD bit rates consist of a combination of nominal and data bit rate. To make it easier to use such bit rate combinations, they can be combined here to form bit rate presets.

## CAN (SJA1000) Tab

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

Clock Frequency

The bit timing of SJA1000 bit rates is based on the clock frequency of 8 MHz, so there are no further entries to choose from.

Bit Rate

This list shows all available bit rates that are based on the clock frequency 8 MHz.

To create a new bit rate, click on the button below the list. Now you can either enter the desired bit rate directly in the table in the lower area of the dialog window in the Bit Rate column, or the 16-bit BTR0/BTR1 code, or manually adjust the individual parameters (Prescaler / TSEG1 / TSEG2 / SJW). If you enter a value for the bit rate that cannot be achieved, a message window opens that suggests the next possible value that has been calculated.

For more information about the bus timing registers BTR0 and BTR1, refer to the Philips SJA1000 Stand-alone CAN controller data sheet, chapters 6.5.1 and 6.5.2.

With the button you can open a selection list with possible parameter combinations, which lead to the same bit rate but may result in different sample points.

To delete a bit rate, select the bit rate in the list and click on the button below the list. Note that only user-defined bit rates can be deleted.

## CAN Tab

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

Clock Frequency

Selects a clock frequency on which the bit timing of the bit rate should be based. After you have selected a clock frequency, the Bit rate list shows all the bit rates in the database that are based on the selected clock frequency.

Bit Rate

This list shows all available bit rates that are based on the selected clock frequency.

To create a new bit rate, click on the button below the list. Now you can either enter the desired bit rate and sample point directly in the table in the lower area of the dialog window in the Bit Rate and Sample Point columns, or manually adjust the individual parameters (Prescaler / TSEG1 / TSEG2 / SJW). If you enter a value for the bit rate that cannot be achieved, a message window opens that suggests the next possible value that has been calculated.

With the button you can open a selection list with possible parameter combinations, which lead to the same bit rate but may result in different sample points.

To delete a bit rate, select the bit rate in the list and click on the button below the list. Note that only user-defined bit rates can be deleted.

## CAN FD Tab

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

Bit Rate Preset

This list contains all available bit rate presets. When you select a preset, the associated nominal and data bit rates are selected in the corresponding lists, and the clock frequency on which the bit rates are based is highlighted in the Clock Frequency list.

To create a new preset, click on the button below the list. Then select the clock frequency on which the bit rates are based, and select the nominal and data bit rates for your preset.

Via the context menu (accessible from the right mouse button), you can copy a preset to the Clipboard, or paste a preset from the Clipboard into the list.

To delete a preset, select the preset in the list and click on the button below the list. Note that only user-defined presets can be deleted. Note that only user-defined presets can be deleted.

If you have selected a user-defined preset and changed one of its bit rates, an asterisk character is shown behind the preset name in the list. If you have made the changes inadvertently, you can either click the Cancel button to close the dialog window and discard all changes, or choose the Revert changes command for the preset from the context menu.

Clock Frequency

Chooses a clock frequency for a preset. All bit rates available for the chosen frequency are shown in the corresponding lists.

The selected entry in the list can only be changed when either a user-defined preset is selected or when the entry None is selected in the Bit Rate Preset list.

Nominal Bit Rate

This list shows all available nominal bit rates that are based on the selected clock frequency.

To create a new nominal bit rate, first choose the entry None in the Bit Rate Preset list, or create a new user-defined preset. Then click on the button below the list. Now you can either enter the desired bit rate and sample point directly in the table in the lower area of the dialog window in Nominal row and the Bit Rate and Sample Point columns, or manually adjust the individual parameters (Prescaler / TSEG1 / TSEG2 / SJW). If you enter a value for the bit rate that cannot be achieved, a message window opens that suggests the next possible value that has been calculated.

With the button you can open a selection list with possible parameter combinations, which lead to the same nominal bit rate but may result in different sample points.

To delete a bit rate, select the bit rate in the list and click on the button below the list. Note that only user-defined bit rates can be deleted.

As long as a predefined preset is selected, the Nominal Bit Rate list is locked for selection and modification.

Data Bit Rate

This list shows all available data bit rates that are based on the selected clock frequency.

To create a new data bit rate, first choose the entry None in the Bit Rate Preset list, or create a new user-defined preset. Then click on the button below the list. Now you can either enter the desired bit rate and sample point directly in the table in the lower area of the dialog window in Data row and the Bit Rate and Sample Point columns, or manually adjust the individual parameters (Prescaler / TSEG1 / TSEG2 / SJW). If you enter a value for the bit rate that cannot be achieved, a message window opens that suggests the next possible value that has been calculated.

With the button you can open a selection list with possible parameter combinations, which lead to the same nominal bit rate but may result in different sample points.

To delete a bit rate, select the bit rate in the list and click on the button below the list. Note that only user-defined bit rates can be deleted.

As long as a predefined preset is selected, the Data Bit Rate list is locked for selection and modification.

Note
When combining nominal and data bit rates to presets, the values of the prescalers for both nominal and data bit rate should be identical to ensure trouble-free operation.

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