CLK – Clock generators

The B-Box RCP and B-Board PRO digital controllers hold 4 clock generators, which provide time-bases to use with various peripherals such as the PWMs and the control task routine. In a multi-device configuration, the clocks are propagated to all the devices and stay synchronized within ±2 ns.

Features:

• Variable frequency: the clock generators support glitch-less reconfiguration during execution as explained in Variable frequency operation with the B-Box/B-Board (PN121).
• Synchronization: in a multi-device configuration, all clock generators are intrinsically synchronized.
• Simultaneous reset: all the clock generators are reset at the same time. It implies that, if the frequency of a clock generator is a multiple of another one, they are guaranteed to stay in phase (e.g. 20kHz and 40 kHz).

Simulink block

Signal specification

• The output can be wired to a PWM block input signal > to set its switching frequency.
• The input is only visible if the variable parameter is selected and it sets the frequency of the clock during real-time execution.

Standard parameters

• Clock ID selects which clock generator to configure. (CLOCK_0 is already used by the CONFIG block and cannot be instantiated in a separate clock block.)
• Initial clock frequency configures the frequency of the clock in Hertz (Hz). If the desired frequency is not achievable (because of the peripheral resolution of 4 ns), the clock frequency is replaced by the closest achievable frequency and a warning is generated in BB Control utility software.
  This value is overwritten by the input signal value during run-time if the frequency is configured as Variable. In simulation, this value is used as the initial value during the first clock period.

Advanced parameters

• Frequency value the option “variable frequency“ enables the reconfiguration of the clock frequency during real-time execution using the input signal.
• Frequency limits sets the minimal and maximal frequencies that the clock generator uses as saturation points.

PLECS block

Signal specification

• The output can be wired to a PWM block input signal > to set its switching frequency.
• The input is only visible if the frequency value is set as variable frequency and it sets the frequency of the clock during real-time execution.

Standard parameters

• Clock ID selects which clock generator to configure. (CLOCK_0 is already used by the CONFIG block and cannot be instantiated in a separate clock block.)
• Initial clock frequency configures the frequency of the clock in Hertz (Hz). If the desired frequency is not achievable (because of the peripheral resolution of 4 ns), the clock frequency is replaced by the closest achievable frequency and a warning is generated in BB Control utility software.
  This value is overwritten by the input signal value during run-time if the frequency is configured as Variable. In simulation, this value is used as the initial value during the first clock period.

Advanced parameters

• Frequency value the option “variable frequency“ enables the reconfiguration of the clock frequency during real-time execution using the input signal.
• Frequency limits sets the minimal and maximal frequencies that the clock generator uses as saturation points.

C++ functions

void Clock_SetFrequency(tClock clock, float freq);Code language: C++ (cpp)

void Clock_SetPeriod(tClock clock, unsigned int period);Code language: C++ (cpp)

void Clock_SetPrescaler(tClock clock, unsigned int prescaler);Code language: C++ (cpp)

void Clock_ConfigureAsRealTimeTunable(tClock clock);Code language: C++ (cpp)