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DsPIC Block/Change Notification

From - Simulink device driver Blockset for dsPIC / PIC24 / PIC32 Microcontrollers --[[User:LubinKerhuel|LubinKerhuel]] 12:40, 3 September 2009 (UTC)
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Block Change Notification

The Change Notification (CN) block allow to detect a change on one or several inputs. This peripheral can also be used to measure the duration of a pulse (like PWM) on all CN ports of dsPIC / PIC24. Note that this block used in PWM input mode is less robust than Input Capture peripheral.

Dialog Box Parameters

Change Notification Dialog

Input Channel

Specify Change Notification channel(s) (CN) starting from 1. Specify multiple channels as a vector. This will also set the block's number of output.

Channel Input Type

Select for each channel which measurement you want to extract.

  • 1 : get the High pulse duration
  • 2 : get the Low pulse duration
  • 3 : get both High and low pulse duration
  • 4 : get the periode using rising edge
  • 8 : get the periode using falling edge
  • 5 : get both High pulse duration and periode using rising edge
  • 10 : get both Down pulse duration and periode using falling edge
  • The position value in the vector refers to corresponding channel defined in "Input Channels".


Define for each channel the max time in secondes of the slowest event to be measured by the corresponding channel.

Safety Margin in %

Add a margin to the max time defined previously. This margin time allow correct measurement, provided the event is larger than the max attempted value.

ValMax / Channel Variable Name

This Variable will be evaluated in the workspace and allow you to scale the data.The ValMax is the max value that will be given by an event of the duration defined in Max/Channels. This value does not take into account the Safety margin.

Result Byte Resolution

This is the log2 of the ValMax Variables for each channels (corresponding to the number of bits coding the information).


This is the timer which is used by the corresponding channel. It is set automatically when the diagram is updated or compiled. The timer prescaler are defined in the Master block.

Change Detected on

Add outputs to the block. For each channel, you can know if a change appears. The output is set to 1 either on rising edge, falling edge or both.

Pull up

for each channel, 1 mean internal Pul-up resistor connected ; 0 mean Pull up not disconnected.

Sample Time

-1 mean inherited

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