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Chapter 17
Clocked Serial Interface (CSIB)
Preliminary User’s Manual U17566EE1V2UM00
(4)
CBnSTR - CSIBn status register
CBnSTR is an 8-bit register that displays the CSIBn status.
Access
This register can be read/written in 8-bit or 1-bit units.
Bit CBnTSF is read-only.
Address
<base> + 3
H
Initial Value
00
H
. This register is cleared by any reset.
In addition to reset input, the CBnSTR register can be initialized by clearing the
CBnCTL0.CBnPWR bit to 0.
Note
In case of an overrun error, the reception error interrupt INTCBnRE behaves
different, depending on the transfer mode:
• Continuous transfer mode
The reception error interrupt INTCBnRE is generated instead of the
reception completion interrupt INTCBnR.
• Single transfer mode
No interrupt is generated.
In either case the overflow flag CBnSTR.CBnOVE is set to 1 and the previous
data in CBnRX will be overwritten with the new data.
7
6
5
4
3
2
1
0
CBnTSF
0
0
0
0
0
0
CBnOVE
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Table 17-7
CBnSTR register contents
Bit position
Bit name
Function
7
CBnTSF
Communication status flag
0: Communication stopped
1: Communicating
During transmission, this register is set when data is prepared in the CBnTX
register, and during reception, it is set when a dummy read of the CBnRX register
is performed.
When transfer ends, this flag is cleared to 0 at the last edge of the clock.
0
CBnOVE
Overrun error flag
0: No overrrun
1: Overrun
•
An overrun error occurs when the next reception starts without performing a
CPU read of the value of the receive buffer, upon completion of the receive
operation.
The CBnOVE flag displays the overrun error occurrence status in this case.
•
The CBnOVE flag is cleared by writing 0 to it. It cannot be set even by writing
1 to it.
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