UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 615

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

Remarks 1. If automatic block transmission request bit ABTTRG is set to 1 in the normal operation mode with
1(high)
2
3
4
5(low)
Priority
3. m = 0 to 15
2. When changing the contents of a transmit buffer, the RDY flag of this buffer must be cleared before
ABT, the TRQ bit is set to 1 only for one message buffer in the ABT message buffer group.
If the ABT mode was triggered by ABTTRG bit, one TRQ bit is set to 1 in the ABT area (buffer 0
through 7). Beyond this TRQ bit, the application can request transmissions (set TRQ to 1) for other
TX-message buffers that do not belong to the ABT area. In that case an interval arbitration process
(TX-search) evaluates all TX-message buffers with TRQ bit set to 1 and chooses the message buffer
that contains the highest prioritized identifier for the next transmission.
identifiers that have the highest priority (i.e. identical identifiers), the message located at the lowest
message buffer number is transmitted at first.
Upon successful transmission of a message frame, the following operations are performed.
- The TRQ flag of the corresponding transmit message buffer is automatically cleared to 0.
- The transmission completion status bit CINTS0 of the C0INTS register is set to 1 (if the interrupt
- An interrupt request signal INTC0TRX output (if the CIE0 bit of the C0IE register is set to 1 and if
updating the buffer contents.
temporarily, the status of RDY must be checked by software, after changing it.
enable bit (IE) of the corresponding transmit message buffer is set to 1).
the interrupt enable bit (IE) of the corresponding transmit message buffer is set to 1).
Value of first 11 bits of ID
[ID28 to ID18]:
Frame type
ID type
Value of lower 18 bits of ID
[ID17 to ID0]:
Message buffer number
Conditions
Preliminary User’s Manual U19748EJ1V0UD
CHAPTER 15 CAN CONTROLLER
As during internal transfer actions, the RDY flag may be locked
The message frame with the lowest value represented by the first
11 bits of the ID is transmitted first. If the value of an 11-bit
standard ID is equal to or smaller than the first 11 bits of a 29-bit
extended ID, the 11-bit standard ID has a higher priority than
message frame with the 29-bit extended ID.
A data frame with an 11-bit standard ID (RTR bit is cleared to 0)
has a higher priority than a remote frame with a standard ID and a
message frame with an extended ID.
A message frame with a standard ID (IDE bit is cleared to 0) has a
higher priority than a message frame with an extended ID.
If more than one transmission-pending extended ID message frame
have equal values in the first 11 bits of the ID and the same frame
type (equal RTR bit values), the message frame with the lowest
value in the lower 18 bits of its extended ID is transmitted first.
If two or more message buffers request transmission of message
frames with the same ID, the message from the message buffer
with the lowest message buffer number is transmitted first.
Description
If there are 2 or more
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