Network SSP Serial Port

Figure 16-14. National Semiconductor Microwire with SSCR1[TTE]=1

SSPSCLK SSPSFRM

SSPTXD

Bit[7] or

Bit[0]

Bit[15]

 

8 or 16-Bit Control

SSPRXD

Undefined

Bit[N] Undefined Bit[0]

Undefined

4 to 32 Bits

A9977-01

Note: SSCR1[TTELP] must be 0 for National Semiconductor Microwire.

16.4.4.4Programmable 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 16-15shows the pin timing for this mode.

Figure 16-15. PSP mode with SSCR1[TTE]=1 and SSCR1[TTELP]=0 (slave to frame)

SSPSCLK

 

 

 

 

(when SCMODE = 0)

 

 

 

 

SSPSCLK

 

 

 

 

(when SCMODE = 1)

 

 

 

 

SSPSCLK

 

 

 

 

(when SCMODE = 2)

 

 

 

 

SSPSCLK

 

 

 

 

(when SCMODE = 3)

 

 

 

 

SSPTXD

 

MSB

LSB

 

T1

T2

 

T3

T4

SSPRXD

Undefined

MSB

LSB

Undefined

SSPSFRM

(when SFRMP = 1)

T5T6

SSPSFRM

(when SFRMP = 0)

A9978-01

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 16-16shows the pin timing for this mode.

Intel® PXA255 Processor Developer’s Manual

16-15

Page 557
Image 557
Intel PXA255 manual Programmable Serial Protocol