R01UH0823EJ0100 Rev.1.00 Page 1312 of 1823
Jul 31, 2019
RX23W Group 37. Serial Sound Interface (SSI)
37.2.4 FIFO Status Register (SSIFSR)
Note 1. Writing 0 after confirming the flag to be 1 clears the flag. To clear flags, write 0 only to the flags to be cleared; write 1 to the other
flags. Do not write 0 to a status flag indicating 0.
Note 2. Since the SSIFTDR register is an 8-stage FIFO register, the amount of data that can be written to it while TDE flag = 1 is “8 -
specified transmit FIFO threshold value” bytes at maximum. Writing more data will be ignored. The number of data bytes in the
SSIFTDR register is indicated in the TDC[3:0] flags.
The SSIFSR register consists of status flags indicating the operating status of the SSIFTDR register and SSIFRDR
register.
RDF Flag (Receive Data Full Flag)
This flag indicates that, when the received data is transferred to the SSIFRDR register, the number of data bytes in the
SSIFRDR register has become equal to or greater than the receive FIFO threshold value, and thus reading the received
data from the SSIFRDR register has been enabled.
[Setting condition]
The number of receive data bytes that is equal to or greater than the value specified by the SSIFCR.RTRG[1:0] bits
is stored in the SSIFRDR register.
[Clearing conditions]
0 is written to the RDF flag after the RDF flag is confirmed to be 1.
Received data is read from the SSIFRDR register using DMA or DTC transfer (transfer of the last block in block
transfer). Do not clear the RDF flag to 0 during DMA or DTC transfer.
Address(es): SSI0.SSIFSR 0008 A514h
b31 b30 b29 b28 b27 b26 b25 b24 b23 b22 b21 b20 b19 b18 b17 b16
———— TDC[3:0] ———————TDE
Value after reset:
0000000000000001
b15b14b13b12b11b10b9b8b7b6b5b4b3b2b1b0
———— RDC[3:0] ———————RDF
Value after reset:
0000000000000000
Bit Symbol Bit Name Description R/W
b0 RDF Receive Data Full Flag 0: Number of received data bytes in the SSIFRDR register is
less than the specified receive FIFO threshold value.
1: Number of received data bytes in the SSIFRDR register is
equal to or greater than the specified receive FIFO threshold
value.
R/(W)
*
1
b7 to b1 — Reserved These bits are read as 0. The write value should be 0. R/W
b11 to b8 RDC[3:0] Receive Data Indicate Flag Indicate the number of data units stored in the SSIFRDR
register.
R
b15 to b12 — Reserved These bits are read as 0. The write value should be 0. R/W
b16 TDE Transmit Data Empty Flag 0: Number of data bytes for transmission in the SSIFTDR
register is greater than the specified transmit FIFO threshold
value.
1: Number of data bytes for transmission in the SSIFTDR
register is equal to or less than the specified transmit FIFO
threshold value.*
2
R/(W)
*
1
b23 to b17 — Reserved These bits are read as 0. The write value should be 0. R/W
b27 to b24 TDC[3:0] Transmit Data Indicate Flag Indicate the number of data units stored in the SSIFTDR
register.
R
b31 to b28 — Reserved These bits are read as 0. The write value should be 0. R/W
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