Intel PXA255 - Manual (Page 555)

Intel® PXA255 Processor Developer’s Manual 16-15
Network SSP Serial Port
Note: SSCR1[TTELP] must be 0 for National Semiconductor Microwire.
16.4.4.4 Programmable Serial Protocol
When SSCR1[TTE] is 0, the SSP behaves as described in Section 16.4.3.4 .
If SSCR1[TTE] is 1 and SSCR1[TTELP] is 0, SSPTXD is driven at the same clock edge that the
MSB is driven. If the SSP is a slave to frame SSPTXD is Hi-Z on the clock edge after the edge that
starts the LSB.
Figure 16-15 shows the pin timing for this mode.
If the SSP is a master to frame, SSPTXD is Hi-Z two clock edges after the clock edge that drives
the LSB. This occurs even if the SSP is a master of clock and this clock edge does not appear on
the SSPSCLK.
Figure 16-16 shows the pin timing for this mode.
Figure 16-14. National Semiconductor Microwire with SSCR1[TTE]=1
A9977-01
SSPRXD
SSPSFRM
SSPSCLK
SSPTXD
4 to 32 Bits
Bit[7] or
Bit[15]
8 or 16-Bit Control
Bit[0]
Bit[N] Bit[0] Undefined Undefined Undefined
Figure 16-15. PSP mode with SSCR1[TTE]=1 and SSCR1[TTELP]=0 (slave to frame)
A9978-01
MSB
Undefined Undefined
T1 T2 T3 T4
LSB
MSB LSB
T6 T5
SSPSCLK
(when SCMODE = 0)
SSPSCLK
(when SCMODE = 1)
SSPSCLK
(when SCMODE = 2)
SSPSCLK
(when SCMODE = 3)
SSPSFRM
(when SFRMP = 1)
SSPSFRM
(when SFRMP = 0)
SSPTXD
SSPRXD