SH7760 Datasheet, PDF (756/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

The word select pin in this mode does not act as a system word start signal as in non-compressed
mode, but instead is used to indicate that the receiver can receive another data burst, or the
transmitter can transmit another data burst.
Figures 20.18 and 20.19 show the compressed mode data transfer, with burst mode disabled, and
enabled, respectively.
TRMD = 1, CPEN = 1, SCKD = 1, SWSD = 0, SWSP = 0, BREN = 0
SSI_SCK
SSI_WS
SSI_SDATA
MSB
LSB MSB
LSB
Data word 1
Data word 2
Null data
MSB
LSB
Data word 3
Figure 20.18 Compressed Data Format, Slave Transmitter, Burst Mode Disabled
TRMD = 1, CPEN = 1, SCKD = 1, SWSD = 0, SWSP = 0, BREN = 1
SSI_SCK
SSI_WS
SSI_SDATA ^MSB
LSB MSB
LSB
Data word 1
Data word 2
MSB
LSB
Null data
Data word 3
Figure 20.19 Compressed Data Format, Slave Transmitter, and Burst Mode Enabled
(1) Slave Receiver
This mode allows the module to receive a serial bit stream from another device and store it in
memory.
The shift register clock can be supplied from an external device or from an internal clock.
The word select pin is used as an input flow control. Assuming that SWSP = 0 if SSI_WS is high
then the module will receive the bit stream in blocks of 32 bits, one data bit per clock. If SSI_WS
goes low then the module will complete the current 32-bit block and then stop any further
reception, until SSI_WS goes high again.
Rev. 1.0, 02/03, page 706 of 1294