R01UH0823EJ0100 Rev.1.00
Page 1314 of 1823
Jul 31, 2019
RX23W Group
37. Serial Sound Interface (SSI)
37.2.5
Transmit FIFO Data Register (SSIFTDR)
The SSIFTDR register is a write-only FIFO register consisting of eight stages of 32-bit registers for storing transmit data.
Write transmit data to the SSIFTDR register in 64-bit (two stages of FIFO) units regardless of the data word length
setting. If transmit data ends on a 32-bit boundary, write 00000000h for the other 32 bits, and stop transmission while 64-
bit writing is completed. When the transmit shift register is empty, the SSI transfers the transmit data written to the
SSIFTDR register to start serial transmission, which can be continued until the SSIFTDR register becomes empty.
Note that when the SSIFTDR register is full of data (32 bytes), the next data cannot be written to it. If writing is
attempted, it will be ignored and an overflow occurs.
37.2.6
Receive FIFO Data Register (SSIFRDR)
The SSIFRDR register is a read-only FIFO register consisting of eight stages of 32-bit registers for storing received data.
Each time 4 bytes of serial data is received, the SSI stores the received serial data in the SSIFRDR register from the
receive shift register according to the
bit setting. Receive operation can be continued until a maximum 32 bytes of
data have been stored to in the SSIFRDR register. The SSIFRDR register can be read but cannot be written to. Note that
when the SSIFRDR register is read when it stores no received data, undefined values will be read and a receive
underflow occurs.
After the SSIFRDR register becomes full of received data, the data received thereafter will be lost and a receive overflow
occurs.
Address(es): SSI0.SSIFTDR 0008 A518h
b31
b30
b29
b28
b27
b26
b25
b24
b23
b22
b21
b20
b19
b18
b17
b16
Value after reset:
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
b15
b14
b13
b12
b11
b10
b9
b8
b7
b6
b5
b4
b3
b2
b1
b0
Value after reset:
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Address(es): SSI0.SSIFRDR 0008 A51Ch
b31
b30
b29
b28
b27
b26
b25
b24
b23
b22
b21
b20
b19
b18
b17
b16
Value after reset:
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
b15
b14
b13
b12
b11
b10
b9
b8
b7
b6
b5
b4
b3
b2
b1
b0
Value after reset:
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—