CY8C28xxx PSoC Programmable System-on-Chip TRM, Document No. 001-52594 Rev. *G
345
Digital Blocks
When SS_ is negated, the SPIS ignores any MOSI/SCLK
input from the master. In addition, the SPIS
is reset, and the MISO output is forced to idle at logic 1. This
allows for a wired-AND connection in a multi-slave environ-
ment. Note that if High-Z output is required when the slave
is not selected, this behavior must be implemented in firm-
ware with I/O writes to the port drive register.
SPIS also supports variable length from 8 bits to 16 bits.
Two adjacent communication blocks can be chained
together to achieve MAX 16-bit SPI. Note the last DCC
block in one row can be chained with the first DCC block in
the next row. SPIS variable length configuration is identical
to variable length configuration in SPIM.
17.1.13.1
Usability Exceptions
The following are usability exceptions for the SPI Slave
function:
1. CR1 is not writeable when the SPIS is enabled.
17.1.13.2
Block Interrupt
The SPIS block has a selection of two interrupt sources:
Interrupt on TX Reg Empty (default) or interrupt on SPI
Complete (same selection as the SPIM). Mode bit 1 in the
function register controls the selection.
If SPI Complete is selected as the block interrupt, the control
register must still be read in the interrupt routine so that this
status bit is cleared; otherwise, no subsequent interrupts are
generated.
17.1.14
Asynchronous Transmitter and Receiver Functions
The Asynchronous Transmitter and Receiver functions are illustrated in
.
Figure 17-6. Asynchronous Transmitter and Receiver Block Diagram
17.1.14.1
Asynchronous Transmitter Function
In the Transmitter function, DR0 functions as a shift register,
with no input and with the TXD serial
the primary output F1. DR1 is a TX Buffer register and DR2
is unused in this configuration. (Refer to the timing diagrams
for this function on page
Unlike SPI, which has no output latency, the TXD output has
one cycle of
. This is because a mux at the output
must select which bits to shift out: the shift register data,
framing bits,
, or mark bits. The output of this mux is
registered to remove glitches. When the block is first
enabled or when it is idle, a mark bit (logic 1) is output.
The
is a free running divide-by-eight cir-
cuit. Although dividing the clock is not necessary for the
Transmitter function, the Receiver function does require a
divide by eight for input sampling. It is also done in the
Transmitter function, to allow the TX and RX functions to run
off the same baud rate generator.
There are two formats supported: A 10-bit frame size includ-
ing one start bit, eight data bits, and one
or an 11-bit
frame size including one start bit, eight data bits, one parity
bit, and one stop bit.
The parity generator can be configured to output either even
or odd parity on the eight data bits.
PSoC
®
RX
Vss
CMOS Input
TX
DCCx2
RX
DCCx3
TX
CMOS Output
RS232 Output
RS232 Input
C1
RS232
Drivers/Receivers,
such as MAX232
Содержание CY8C28 series
Страница 65: ...64 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G RAM Paging ...
Страница 85: ...84 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Internal Main Oscillator IMO ...
Страница 93: ...92 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G External Crystal Oscillator ECO ...
Страница 97: ...96 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Phase Locked Loop PLL ...
Страница 125: ...124 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Страница 311: ...310 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G IDAC_CR0 1 FDh ...
Страница 317: ...316 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Страница 393: ...392 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Страница 425: ...424 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Analog Reference ...
Страница 461: ...460 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Two Column Limited Analog System ...
Страница 477: ...476 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Digital Clocks ...
Страница 483: ...482 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Multiply Accumulate MAC ...
Страница 513: ...512 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Internal Voltage Reference ...
Страница 523: ...522 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Switch Mode Pump SMP ...
Страница 533: ...532 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G I O Analog Multiplexer ...
Страница 537: ...536 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Real Time Clock RTC ...
Страница 561: ...560 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...