Intel® PXA255 Processor Developer’s Manual
16-11
Network SSP Serial Port
clocks programmed in the field SSPSP[SFRMP]. The SSPSFRM remains asserted for the number
of half-clocks programmed within SSPSP[SFRMWDTH]. Four to 32-bits can be transferred per
frame. Once the LSB transfers, the SSPSCLK continues toggling based on the dummy stop field
(SSPSP[DMYSTOP]). SSPTXD either retains the last value transmitted or is forced to zero,
depending on the value programmed within the end of transfer data state field (SSPSP[ETDS]),
when the controller goes into idle mode, unless the SSP is disabled or reset (which forces SSPTXD
low). Refer to
Table 16-2
for more information.
With the assertion of SSPSFRM, receive data is simultaneously driven from the peripheral on
SSPRXD, MSB first. Data transitions on SSPSCLK based on the serial clock mode selected and
are sampled by the controller on the opposite edge. When the SSP is a master to the frame sync
(SSPSFRM) and a slave to the clock (SSPSCLK), at least three extra clocks are needed at the
beginning and end of each block of transfers to synchronize internal control signals (a block of
transfers is a group of back-to-back continuous transfers).
Figure 16-9. Programmable Serial Protocol (multiple transfers)
A9523-02
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
MSB
Undefined
T1
T2
T3
T3
MSB
LSB
End of
Transfer
Data State
LSB
End of Transfer
Data State
MSB
MSB
LSB
LSB
T1
T2
T6
T5
T5
T6
T4
Undefined
Undefined
Un-
defined
Содержание PXA255
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Страница 310: ...7 46 Intel PXA255 Processor Developer s Manual LCD Controller ...
Страница 330: ...8 20 Intel PXA255 Processor Developer s Manual Synchronous Serial Port Controller ...
Страница 358: ...9 28 Intel PXA255 Processor Developer s Manual I2 C Bus Interface Unit ...
Страница 488: ...13 36 Intel PXA255 Processor Developer s Manual AC 97 Controller Unit ...
Страница 572: ...16 30 Intel PXA255 Processor Developer s Manual Network SSP Serial Port ...
Страница 599: ...Intel PXA255 Processor Developer s Manual 17 27 Hardware UART ...
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