Table 25. Automatically update of RX3_STATUS register
RX3
RX3
RX3
RX3
Rx3
Rx3
Rx3
Rx3
RX3_STATUS
Reserved
reserved
reserved
extfr
DLC3
DLC2
DLC1
DLC0
X
X
X
0
0
0
0
0
RX3
RX3
RX3
RX3
Rx3
Rx3
Rx3
Rx3
RX3_STATUS
Reserved
reserved
reserved
extfr
DLC3
DLC2
DLC1
DLC0
X
X
X
0
1
0
0
0
The arbitration registers of the RX3 message object will store the arbitration of the
received message and the data registers of the RX3 message object will store the data
of the received message. At the end of frame, the INT will be generated and the action
that the MCU must perform could be the followings (these operations are only read
operations and the internal registers of the AT7908E are not updated):
Operation 8
read reg 06 H
(STATUS_RX register)readout of AT7908E status_rx: rxok3, rxok2, rxok1 indicates the
message object that received the message(if 00 the message is not received). For
example : reg 06 = 04Hex => the message has been received correctly on message
object 3.
read reg 4C H
(RX3_STATUS register)readout of message object 3 status. Is possible to check
extended or standard frame of received message and length of received message. For
example : reg 4C = 08Hex, standard frame, length =8.
read reg 40 H
read reg 41 H
(RX3_ARB_n registers)readout of stored message identifier
read reg 44 H
read reg 45 H
read reg 46 H
read reg 47 H
read reg 48 H
read reg 49 H
read reg 4A H
read reg 4B H
(RX_3_MESSAGE_n register)readout of stored message data.
After the read out of the received message, the MCU must clear the receiver message
object status (principally Rxok bit) and the INT signal setting RXCLRn bit in the
37
AT7908E
4268D–AERO–11/09
ATMEL [ ATMEL ]
