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CY8C28xxx PSoC Programmable System-on-Chip TRM, Document No. 001-52594 Rev. *G
Digital Blocks
Figure 17-31. Mode 0 and 1 Transfer in Progress
illustrates TX data loading in modes 2 and 3. In
this case, there is no dependence on SS and a transfer in
progress is defined to be from the leading edge of the first
SCLK to the point at which the RX Buffer register is loaded
with the received byte. Loading the shifter by the leading
edge of the clock has the effect of providing the required
one-half clock setup time, as the data is latched into the
receiver on the trailing edge of the SCLK in these modes.
Figure 17-32. Mode 2 and 3 Transfer in Progress
Chained SPIS.
When two adjacent communication blocks
are chained to form a more-than-8-bit SPIS function, the
preceding SPIS operations are maintained the same, with
the following exceptions:
■
More transits for more bits.
■
Only need to enable LSB block to enable the function
such as in chained Timer/Counter/CRCPRS/PWMDBL
functions.
■
Need to write MSB TX register first and then LSB regis-
ter to set new data.
■
Always read MSB RX data first and then LSB RX data.
■
Always check LSB status bits for whole SPIM status if
you follow above TX/RX read/write operation sequence.
■
The interrupt in both blocks can be enabled and selected
arbitrarily. (But if clearing SPI Complete bit or TX Empty
bit, still need to read the CR0 register or write DR1 regis-
ter in that block).
SCLK (Mode 1)
SCLK (Mode 0)
SS Forced Low
SS Toggled on a Message Basis
SS Toggled on Each Byte
SS
Transfer in Progress
SCLK (Mode 1)
SCLK (Mode 0)
SS
Transfer in Progress
Transfer in Progress
SCLK (Mode 1)
SCLK (Mode 0)
SS
Transfer in Progress
Transfer in Progress
SCLK (Mode 3)
SCLK (Mode 2)
Transfer in Progress
(No Dependance on SS)
Summary of Contents for CY8C28 series
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