UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 621

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

15.11 Power Save Modes
15.11.1 CAN sleep mode
consumption. The CAN module can enter the CAN sleep mode from all operation modes. Release of the CAN sleep
mode returns the CAN module to exactly the same operation mode from which the CAN sleep mode was entered.
issued or pending.
The CAN sleep mode can be used to set the CAN controller to standby mode in order to reduce power
In the CAN sleep mode, the CAN module does not transmit messages, even when transmission requests are
(1) Entering CAN sleep mode
The CPU issues a CAN sleep mode transition request by writing 01B to the PSMODE [1:0] bits of the
C0CTRL register.
This transition request is only acknowledged only under the following conditions.
- The CAN module is already in one of the following operation modes
- The CAN bus state is bus idle (the 4th bit in the interframe space is recessive)
- No transmission request is pending
If any one of the conditions mentioned above is not met, the CAN module will operate as follows.
- If the CAN sleep mode is requested from the initialization mode, the CAN sleep mode transition request is
- If the CAN bus state is not bus idle (i.e., the CAN bus state is either transmitting or receiving) when the CAN
- If a request for transition to the initialization mode and a request for transition to the CAN sleep are made at
Note If the CAN bus is fixed to dominant, the request for transition to the CAN sleep mode is held pending.
Remark If a sleep mode request is pending, and at the same time a message is received in a message
ignored and the CAN module remains in the initialization mode.
sleep mode is requested in one of the operation modes, immediate transition to the CAN sleep mode is not
possible. In this case, the CAN sleep mode transition request is held pending until the CAN bus state
becomes bus idle (the 4th bit in the interframe space is recessive). In the time from the CAN sleep mode
request to successful transition, the PSMODE [1:0] bits remain 00B. When the module has entered the
CAN sleep mode, PSMODE [1:0] bits are set to 01B.
the same time while the CAN module is in one of the operation modes, the request for the initialization
mode is enabled. The CAN module enters the initialization mode at a predetermined timing. At this time,
the CAN sleep mode request is not held pending and is ignored.
- Normal operation mode
- Normal operation mode with ABT
- Receive-only mode
- Single-shot mode
- Self-test mode
- CAN stop mode in all the above operation modes
Also the transition from CAN stop mode to CAN sleep mode is independent of the CAN bus state.
box, the sleep mode request is not cancelled, but is executed right after message storage has
been finished. This may result in AFCAN being in sleep mode, while the CPU would execute the
RX interrupt routine. Therefore, the interrupt routine must check the access to the message
buffers as well as reception history list registers by using the MBON flag, if sleep mode is used.
Preliminary User’s Manual U19748EJ1V0UD
CHAPTER 15 CAN CONTROLLER
Note
619