Fujitsu FR81S User Manual
CHAPTER 40: MULTI-FUNCTION SERIAL INTERFACE
4. Registers
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : MULTI-FUNCTION SERIAL INTERFACE
FUJITSU SEMICONDUCTOR CONFIDENTIAL
118
Bit name
Function
bit5 ACKE:
Data byte
acknowledge
enable bit
⋅
If you set "1" to this bit, "L" will be output at the time of acknowledgement.
⋅
This bit may be changed only when any of following conditions is met.
⋅
DMA mode is disabled (SSR:DMA="0"), ACT="1" and INT bit is "1"
⋅
DMA mode is enabled (SSR:DMA="1"), ACT="1" and SSR:TBI bit is "1"
⋅
DMA mode is enabled (SSR:DMA="1"), ACT="1" and SSR:RDRF is "1" when in slave
reception
⋅
ACT="0"
This bit will be disabled on the following conditions.
(1) Acknowledgement for address fields except for reserved address (automatic
generation).
(2) At data transmission (IBSR:RSA="0", IBSR:TRX="1", IBSR:FBT="0").
(3) At slave reception with reception FIFO enable (FCR0:FE="1", MSS="0", ACT="1"),
Always responds with ACK.
(4) When reception FIFO is enabled and WSEL is "0" at master reception (FCR0:FE="1",
MSS="1", ACT="1", WSEL="0"), When the SSR:TDRE bit is "0", responds with
ACK and when the SSR:TDRE bit is 1, responds with NACK.
(5) When reception FIFO is enabled, WSEL is "0", reserved address is detected, and slave
is transmitted (IBSR:RSA="1", IBSR:TRX="1", IBSR:FBT="1"), always responds
with ACK. If you want to respond with NACK, at an interrupt after the detection of
reserved address, disable reception FIFO and set ACKE="0".
(6) When reception FIFO is enabled and WSEL is "1", the transmit data register has data
on master reception (FCR0:FE="1", MSS="1", ACT="1", WSEL="1",
SSR:TDRE="0").
"0": Acknowledge is disabled
"1": Acknowledge is enabled
bit4 WSEL:
Wait select
bit
⋅
When the DMA mode is prohibited (SSR:DMA=0), this bit selects whether an interrupt
is generated (INT="1") before or after acknowledge and I
2
C bus is waited.
⋅
When the DMA mode is permitted (SSR:DMA=1), this bit selects whether an interrupt is
generated (INT="1", SSR:TBI ="1" at transmission, SSR:RDRF ="1" at reception)
before or after acknowledge and I
2
C bus is waited.
⋅
WSEL bit will be disabled on the following condition.
(1) When an interrupt to the first byte*
1
generated (INT=1)
(2) When a reserved address detected (IBSR:FBT="1",IBSR: RSA="1")
(3) While the data transfer is in progress using FIFO and when NACK response *
2
detected (FCR0:FE="1", IBSR:RACK="1", ACT="1")
(4) When reception FIFO is used and reception FIFO becomes FULL
*1: The first byte: indicates data after the (repeat) start condition.
*2: NACK response: indicates that SDA of I
2
C bus is "H" in the acknowledge interval.
"0": Wait after acknowledge (9 bits)
"1": Wait after data transmission/reception is completed (8 bits)
bit3 CNDE:
Condition
detect
interrupt
enable bit
This bit is used to enable interrupts when a stop condition or a repeat start condition is
detected in master mode or in slave mode (ACT="1"). When the RSC bit or the SPC bit in
the IBSR register is "1" and this bit is "1", an interrupt occurs.
"0": Repeat start/stop condition interrupt is disabled
"1": Repeat start/stop condition interrupt is enabled
bit2 INTE:
Interrupt
enable bit
This bit is used to enable interrupts to the data transmission/reception and bus error in
master mode or in slave mode (INT="1").
"0": Interrupt disabled
"1": Interrupt enabled
MB91520 Series
MN705-00010-1v0-E
1431