CR16MCS9VJE8 National Semiconductor, CR16MCS9VJE8 Datasheet - Page 103

• Manufacturer Part Number: CR16MCS9VJE8
• Description: 16-Bit Microcontroller IC
• Manufacturer: National Semiconductor

Specifications of CR16MCS9VJE8

• Controller Family/series: CR16X
• Core Size: 16 Bit
• Program Memory Size: 64K X 8 Flash
• Digital Ic Case Style: PQFP
• No. Of Pins: 80
• Mounting Type: Surface Mount
• Clock Frequency: 25MHz
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

20.6.4
The transmission process can be started after the user has
loaded the buffer registers (data, ID, DLC, PRI) and set the
buffer status from TX_NOT_ACTIVE to TX_ONCE, TX_RTR
or TX_ONCE_RTR.
When the CPU writes TX_ONCE, the buffer will be
TX_BUSY as soon as CR16CAN has scheduled this buffer
for the next transmission. After the frame could be success-
fully transmitted, the buffer status will be automatically reset
to TX_NOT_ACTIVE when a data frame was transmitted or
to RX_READY when a remote frame was transmitted.
TX Buffer States
RTR
received
transmit failed
*1: TX request delayed
TX_ONCE_RTR
priority message
by a TX request of higher
TX_BUSY2
TX_RTR
1010
1111
1110
RX_READY
TX done
CAN
schedules TX
0010
Figure 66. Transmit Buffer States
transmit
request cancelled
CPU writes 1000
CPU writes 1010
TX request
CPU writes 1100
TX_ONCE
1100
Remote transmission
request sent - now wait
to receive a data frame
103
If
TX_ONCE_RTR, it will transmit its data contents. During the
transmission the buffer state is 1111
into the status section of the CNSTAT register. After the suc-
cessful transmission the buffer enters the TX_RTR state and
waits for a remote frame. When it receives a remote frame, it
will go back into the TX_ONCE_RTR state, transmit its data
bytes and return to TX_RTR. If the CPU writes 1010
buffer status section, it will only enter the TX_RTR state. But
it will not send its data bytes before it waits for a remote
frame. Figure 66 illustrates the possible transmit buffer
states.
the
TX request
CPU writes 1110
*1
CPU
schedules TX
CAN
configures
TX_NOT_ACTIVE
TX_BUSY0
transmit failed
1101
1000
request cancelled
CPU writes 1000
transmit
the
TX done
2
as the CPU wrote 1110
message
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buffer
2
into the
to
2