TSS463 ATMEL Corporation, TSS463 Datasheet - Page 44

• Manufacturer Part Number: TSS463
• Description: VAN Data Link Controller with Serial Interface
• Manufacturer: ATMEL Corporation

Message Types
44
TSS463B
There are 5 basic message types defined in the TSS463B. Two of them (transmit and
receive message types) correspond to the normal frame, and the rest correspond to the
different versions of reply frames.
To transmit a normal data frame on the VAN bus, the user must program an identifier as
a Transmit Message. The TSS463B will then transmit this message on the bus until it
has succeeded or the retry count is exceeded.
The opposite of the transmit message type is the Receive Message type. This message
type will not generate any frames on the bus. Instead, it will listen to the bus until a
frame passes that matches its identifier, with the mask taken into account, and then
receive the data in that frame.
The data received will be stored in the message buffer and the length of the message
received is stored in the first byte of the message buffer.
The actual identifier received is stored in the identifier register itself. This identifier may
differ from the identifier specified in the register due to the effect of the mask register.
Normally this should not interfere with the next identifier comparison since the bits that
may differ are masked via the mask register.
The Reply Request Message type is a demand to transmit on the VAN bus a reply
request. When this message type is programmed, three things can happen.
In the first case no other modules on the bus responded with an in-frame reply, and in
this case the TSS463B will set the message type to the after transmission state. When
this message type is programmed, the TSS463B will listen on the bus for a deferred
reply frame matching this identifier, without transmitting the reply request.
After transmission
After transmission
After transmission
(Waiting for reply)
After reception
Initial setup
Initial setup
Initial setup
(of reply)
RNW
RNW
RNW
0
0
0
0
1
1
1
Reply Request Message
Transmit Message
Receive Message
RTR
RTR
RTR
0
0
1
1
1
1
1
Unchanged
Don’t care
CHTx
CHTx
CHTx
0
1
0
1
1
Unchanged
4102E–AUTO–12/04
Don’t care
CHRx
CHRx
CHRx
0
1
0
0
1