Fujitsu F2MC-8FX Hardware Manual page 394

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CHAPTER 22 I C
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Table 22.5-1 I C Bus Control Register 0 (IBCR00) (2 / 2)
Bit name
SPE:
bit2 Stop detection interrupt
enable bit
WUF:
MCU standby-mode
bit1
wakeup interrupt
request flag bit
WUE:
MCU standby-mode
bit0
wakeup function
enable bit
Note:
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This bit enables or disables stop detection interrupts.
• A stop detection interrupt request is generated if this bit and the IBCR00:SPF bit are both "1".
Setting the bit to "0": Disables stop detection interrupts.
Setting the bit to "1": Enables stop detection interrupts.
This bit is used to detect MCU wakeup from a standby mode (stop or watch mode).
• A wakeup interrupt request is generated if this bit and the IBCR00:WUE bit are both "1".
• This bit is set to "1" if a start condition is detected with the wakeup function enabled (IBCR00:WUE =
1).
Setting the bit to "0": Clears itself (changes the value to "0").
Setting the bit to "1": Leaves its value unchanged without affecting the operation.
• The bit returns "1" when read by a read-modify-write operation.
This bit enables or disables the function to wake up the MCU from standby mode (stop or watch mode).
Setting the bit to "0": Disables the wakeup function.
Setting the bit to "1": Enables the wakeup function.
• If a start condition is detected in stop or watch mode when this bit is "1", a wakeup interrupt request is
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generated to start I C operation.
Write "1" to this bit immediately before the MCU enters the stop or watch mode. To
Note: •
ensure that I
or watch mode, clear (write "0" to) this bit as soon as possible.
• When a wakeup interrupt request occurs, the MCU wakes up after the oscillation stabilization
wait time elapses. To prevent the data loss immediately after wakeup, therefore, the SCL0
must rise as the first cycle and the first bit must be received as data after 100 μs (assuming that
the minimum oscillation stabilization wait time is 100 μs) from the wakeup due to the start of
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I C transmission (upon detection of the falling edge of SDA0).
• During a MCU standby mode, the status flags, state machine, and I
function retain the states they had prior to entering the standby mode. To prevent a hang-up of
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the entire I C bus system, make sure that IBSR0:BB = 0 before entering standby mode.
• The wakeup function does not support the transition of the MCU to stop or watch mode with
IBSR0:BB = 1. If the MCU enters stop or watch mode with IBSR0:BB = 1, a bus error will
occur upon detection of a start condition.
• The wakeup function is useful only when the MCU remains in stop/watch mode. (In PLL stop
mode, for example, the time from wakeup to the start of communication becomes longer than
in stop/watch mode as the PLL oscillation stabilization wait time is required in addition to the
oscillation stabilization wait time.)
The AACKX, INTS, and WUE bits in the IBCR00 register are set to "0" and cannot be written to
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either when I C operation is disabled (ICCR:EN = 0) or when a bus error occurs (IBSR:BER = 1).
Function
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C operation can restart immediately after the MCU wakes up from stop
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C bus outputs for the I C