Internal Processes Of The Can-Prim Interface - Jetter JC-120MC User Manual

10 Programming

Internal processes of the CAN-Prim interface

Introduction
Internal reception of
CAN messages
540
The CAN-Prim interface processes the following tasks independently:
Sending of CAN messages

Reception of CAN messages

Filtering of CAN messages on reception

The CAN-Prim interface receives new CAN messages in the following way:
Step
1 The CAN bus receives a valid CAN message.
2 The CAN-ID matches the receiving mask.
3 The CAN-ID matches the CAN-ID of a message box which has been
configured as inbox.
4 If in R 200010530 + message box
number *20 of the message box
... bit 1 NEW-DAT = 0,
... bit 1 NEW-DAT = 1,
5
R 200010503 FIFO filling level is incremented.
This register shows whether new CAN messages have been received, as
well as the number of messages.
6
The message box number is entered into R 200010504 FIFO data.
This register shows which of the messages boxes has received a new
CAN message.
7
In R 200010500 CAN-Prim Status, bit 1 NEW DAT = 1.
Description
...
... bit 1 NEW-DAT becomes = 1;
proceed with step 5
... bit 2 OVERRUN becomes = 1;
CAN message data are discarded.
... then ...
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