Fujitsu FR81S User Manual
CHAPTER 40: MULTI-FUNCTION SERIAL INTERFACE
8. Operation of I2C
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : MULTI-FUNCTION SERIAL INTERFACE
FUJITSU SEMICONDUCTOR CONFIDENTIAL
343
8.3.4. Data Transmission by Master
If the data direction bit (R/W) is "0", data is sent from the master. The slave responds with ACK or NACK
each time one byte is transmitted. The location where a wait condition develops varies depending on the
IBCR:WSEL bit setting as follows:
Table 8-5 IBCR:WSEL Bit at the Time of Master Data Transmission
(When DMA mode is disabled (SSR:DMA=0))
WSEL
Operation
0
<FIFO Unused>
In the 2nd or subsequent byte, the interrupt flag bit (IBCR:INT) is set to "1" and SCL is set to
"L" to go into the wait state when the SSR:TDRE bit is "1" or after the acknowledgment on the
arbitration lost detection.
<FIFO Used>
If FIFO is enabled, the master will set the interrupt flag(IBCR:INT) to "1" after receiving
acknowledge and then goes to the wait state, when it detects an arbitration lost or finds no valid
data in the transmit data register (SSR:TDRE=1).
1
<FIFO Unused>
In the 2nd or subsequent byte, the interrupt flag bit (IBCR:INT) will be set to "1" and SCL will
be set to "L" to go into the wait state when the SSR:TDRE bit is "1" or after the master
transmitted 1 byte data on the arbitration lost detection.
<FIFO Used>
If FIFO is enabled, the master will transmit data, and then set the interrupt flag (IBCR:INT) to
"1" and wait, when it detects arbitration lost or finds no valid data in the transmit data register
(SSR:TDRE=1).
Table 8-6 IBCR:WSEL Bit at the Time of Master Data Transmission
(When DMA mode is enabled (SSR:DMA=1))
WSEL
Operation
0
<FIFO Unused>
In the 2nd or subsequent byte, after acknowledge is received when the SSR:TDRE bit to "1", the
transmission bus idle flag (SSR:TBI) is set to "1" and SCL is set to "L" to put the bus into the
wait state.
<FIFO Used>
Moreover, if FIFO is enabled, after acknowledge is received when the transmission data register
has lost effective data (SSR:TDRE=1), the transmission bus idle flag (SSR:TBI) is set to "1" to
put the bus into the wait state.
1
<FIFO Unused>
In the 2nd or subsequent byte, after the master transmits the data of one byte when the
SSR:TDRE bit is set to "1", transmission bus idle flag (SSR:TBI) is set to "1" and SCL is set to
"L" to put the bus into the wait state.
<FIFO Used>
Moreover, if the FIFO is permitted, after the master transmits the data of one byte when the
transmission data register has lost effective data (SSR:TDRE=1), the transmission bus idle flag
(SSR:TBI) is set to "1" to put the bus into the wait state.
However, the master sets the interrupt flag (IBCR:INT) after receiving acknowledge regardless of the
IBCR:WSEL setting in the following case:
⋅
If NACK is received except for stop condition setting (IBCR:MSS=0, ACT=1)
The following gives an example of procedure used to transmit data to the slave:
MB91520 Series
MN705-00010-1v0-E
1656