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QSSI Registers
1543
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Quad Synchronous Serial Interface (QSSI)
23.5.3 SSIDR Register (Offset = 0x8) [reset = 0x0]
QSSI Data (SSIDR), offset 0x008
The SSIDR register is 16-bits wide. When the SSIDR register is read, the entry in the receive FIFO that is
pointed to by the current FIFO read pointer is accessed. When a data value is removed by the QSSI
receive logic from the incoming data frame, it is placed into the entry in the receive FIFO pointed to by the
current FIFO write pointer.
When the SSIDR register is written to, the entry in the transmit FIFO that is pointed to by the write pointer
is written to. Data values are removed from the transmit FIFO one value at a time by the transmit logic.
Each data value is loaded into the transmit serial shifter, then serially shifted out onto the
SSInDAT0/SSInTX pin at the programmed bit rate.
When a data size of less than 16 bits is selected, the user must right-justify data written to the transmit
FIFO. The transmit logic ignores the unused bits. Received data less than 16 bits is automatically right-
justified in the receive buffer.
SSIDR is shown in
and described in
Return to
Figure 23-12. SSIDR Register
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
RESERVED
DATA
R-0x0
R/W-0x0
Table 23-8. SSIDR Register Field Descriptions
Bit
Field
Type
Reset
Description
31-16
RESERVED
R
0x0
15-0
DATA
R/W
0x0
QSSI Receive/Transmit Data. A read operation reads the receive
FIFO. A write operation writes the transmit FIFO. Software must
right-justify data when the QSSI is programmed for a data size that
is less than 16 bits. Unused bits at the top are ignored by the
transmit logic. The receive logic automatically right-justifies the data.