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R01UH0336EJ0102 Rev.1.02
Page 1121 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 20 CAN Controller (FCN)
20.9.2
FCN Stop Mode
FCN stop mode can be used to set the CAN controller to stand-by mode to
reduce power consumption. The FCN module can enter FCN stop mode only
from FCN sleep mode. Releasing FCN stop mode causes the FCN module to
enter FCN sleep mode.
FCN stop mode can be released (entering FCN sleep mode) only by setting
FCNnCMCLCTL.FCNnCMCLMDPF[1:0] to 01
B
.
FCN stop mode cannot be
released by a change in the CAN bus state. No message is transmitted even
when transmission requests are issued or pending.
(1)
Entering FCN Stop Mode
A FCN stop mode transition request is issued by setting
FCNnCMCLCTL.FCNnCMCLMDPF[1:0] to 11
B
.
A FCN stop mode transition request is only acknowledged while the FCN
module is in FCN sleep mode. In all other modes, the request is ignored.
Caution
To set the FCN module to FCN stop mode, the module must be in FCN sleep
mode. To confirm that the module is in sleep mode, check that the
FCNnCMCLCTL.FCNnCMCLMDPF[1:0] = 01
B
, and then request transition to
FCN stop mode. If a bus change occurs at the FCN reception pin FCNnRX
while this process is being performed, FCN sleep mode is automatically
released. In this case, the FCN stop mode transition request is not
acknowledged.
(2)
FCN Stop Mode Status
The FCN module is in the following state after it enters FCN stop mode.
• The internal operating clock stops and the power consumption is minimized.
• To wake up the FCN module from the CPU, data can be set to
FCNnCMCLCTL.FCNnCMCLMDPF[1:0], but nothing can be written to other
FCN module registers or bits.
• FCN module registers can be read, except for the FCNnCMLISTR,
FCNnCMRGRX, FCNnCMLOSTR, and FCNnCMTGTX registers.
• FCN message buffer registers cannot be written or read.
• FCNnGMCLCTL.FCNnGMCLSSMO is cleared.
• FCNnDNBMRX registers cannot be read.
• An initialization mode transition request is not acknowledged and is ignored.
(3)
Releasing FCN Stop Mode
FCN stop mode can be released only by writing 01
B
to
FCNnCMCLCTL.FCNnCMCLMDPF[1:0]. After releasing FCN stop mode, the
FCN module enters FCN sleep mode.
When transition to initialization mode is requested while the FCN module is in
FCN stop mode, the request is ignored. The CPU has to release stop mode
and then release the FCN sleep mode before entering initialization mode. It is
impossible to enter another operating mode directly from FCN stop mode not
entering FCN sleep mode. Such request is ignored.
Содержание V850 Series
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