Network SSP Serial Port

Figure 16-12. TI SSP with SSCR[TTE]=1 and SSCR[TTELP]=1

SSPSCLK

SSPSFRM

SSPTXD

 

Bit[N]

Bit[N-1]

Bit[1]

Bit[0]

 

SSPRXD

Undefined

Bit[N]

Bit[N-1]

Bit[1]

Bit[0]

Undefined

 

 

MSB

4 to 32 Bits

LSB

 

A9975-01

Note: If SSPSCLK is an input, the device driving SSPSCLK must provide another clock edge to cause the TXD line to go to Hi-Z.

16.4.4.2Motorola SPI

When SSCR1[TTE] is 0, the SSP behaves as described in Section 16.4.3.2.

If SSCR1[TTE] is 1, SSPTXD is driven only when SSPSFRM is 0. When SSPSFRM is 1, SSPTXD is Hi-Z. During the time between the last falling edge and SSPSFRM rising, SSPSP[EDTS] controls the value driven on SSPTXD. Figure 16-13shows the pin timing for this mode.

Figure 16-13. Motorola SPI with SSCR[TTE]=1

SSPSCLK

SSPSFRM

SSPTXD

 

Bit[N]

Bit[N-1]

Bit[1]

Bit[0]

 

SSPRXD

Undefined

Bit[N]

Bit[N-1]

Bit[1]

Bit[0]

Undefined

 

 

MSB

4 to 32 Bits

LSB

 

A9976-01

Note: SSCR1[TTELP] must be 0 for Motorola SPI.

16.4.4.3National Semiconductor Microwire

When SSCR1[TTE] is 0, the SSP behaves as described in Section 16.4.3.3.

If SSCR1[TTE] is 1, SSPTXD is driven at the same clock edge that the MSB is driven. SSPTXD is Hi-Z after the next rising edge of SSPSCLK for the LSB (1 clock edge after the clock edge that starts the LSB). Figure 16-14shows the pin timing for this mode.

16-14

Intel® PXA255 Processor Developer’s Manual

Page 556
Image 556
Intel PXA255 manual Motorola SPI