hi-3200 Holt Integrated Circuits, Inc., hi-3200 Datasheet - Page 33

• Manufacturer Part Number: hi-3200
• Description: Avionics Data Management Engine / Arinc 429 - Can Bus Bridge
• Manufacturer: Holt Integrated Circuits, Inc.

The Repetition rate register value defines the time
interval between successive starts of the programmed
CAN transmit sequence. The value is set in binary, with
the LSB representing 10 ms.
If the repetition rate is shorter than the minimum time
needed to transmit all CAN frames in the sequence (but
not zero), the transmit sequence will begin again
immediately if the CAN Control Register SKIP bit is a
zero. If the SKIP bit is a one, the sequencer will wait until
the next rollover of the Repetition Rate Counter before
starting a new cycle.
The contents of each CAN frame transmitted in the
sequence is defined by its Frame Descriptor. Each
descriptor consists of one “Descriptor Header Byte” and
from 0 to 24 additional descriptor bytes depending upon,
the descriptor type (type 1 - 3) and the data payload
length. A special descriptor header marks the end of the
descriptor table.
CAN Bus Transmit Descriptor Table
CAN REPETITION RATE REGISTER
(Address 0x8033)
Sequence
Repetition rate
Repetion Rate
pointer
Register
counter
0x79BF
0x6000
Transmit Frame Descriptor n
Transmit Frame Descriptor 5
Transmit Frame Descriptor 4
Transmit Frame Descriptor 0
Transmit Frame Descriptor 3
Transmit Frame Descriptor 2
Transmit Frame Descriptor 1
End of Sequence marker
HOLT INTEGRATED CIRCUITS
MSB
7
Channel Repetition Period
6
HI-3200, HI-3201
5
4
3
33
2
When the Repetition Rate counter is programmed to zero
(default), the transmit sequence shall execute one time
only. A zero - to - one transition of the RUN/STOP bit will
cause the transmit sequence to start. One-time execution
of the sequencer is useful when transmitting CAN frames
directly from the host CPU. One or more immediate-
mode (Type 1) descriptors can be written into the
sequence table, transmitted, and then refreshed for the
next cycle.
make best use of the available descriptor table memory
space while still allowing complete flexibility in defining
frame content and data source. The Descriptor header
byte is of a common format for all three descriptor types.
The CAN Transmit sequence pointer uses information in
the header byte to determine the length of the descriptor
and thus the address of the next descriptor block in the
sequence table.
The three different descriptor types allow the user to
1
LSB
0
Descriptor Header
Descriptor Byte n
Descriptor Byte 2
Descriptor Byte 1
}
0 - 24 Bytes