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Mini57
Apr. 06, 2017
Page 310 of 475
Rev.1.00
MINI5
7
S
E
RI
E
S
TECH
NIC
A
L R
E
F
E
RE
N
CE
MA
N
UA
L
I
2
C:
The timing measurement counter indicates time-out clock cycle.
Sample Time Counter
A sample time counter associated to the protocol related counter defining protocol specific
timings, such shift control signals or bit timings, based on the input frequency
f
SAMP_CLK
. The
sample time counter allows generating time intervals for protocol-specific purposes. The period
of a sample frequency
f
PDS_CNT
is given by the selected input frequency
f
SAMP_CLK
and the
programmed pre-divider value (PDSCNT (USCI_BRGEN [9:8])). The meaning of the sample time
depends on the selected protocol. Please refer to the corresponding chapters for more protocol-
specific information.
f
DS_CNT
f
SAMP_CLK
1
DSCNT+1
Protocol
Processor
Unit
DSCNT
(USCI_BRGEN [14:10])
f
P
DS_CNT
PDSCNT
(USCI_BRGEN[9:8])
Figure 6.11-11 Sample Time Counter
6.11.4.5 Data Transfer Events and Interrupts
The data transfer events are based on the transmission or reception of a data word. The related
indication flags are located in register USCI_PROTSTS. All events can be individually enabled for
interrupt generation. If the FUNMODE (USCI_CTL [2:0]) is set to 0, the USCI is disabled. When
FUNMODE (USCI_CTL [2:0]) is set for a protocol port, the internal states will be controlled by
logic hardware of the selected protocol.
Transmit start interrupt event to indicate that a data word has been started:
A transmit start interrupt event occurs when the data is loaded into transmitted shift register.
It is indicated by flag TXSTIF (USCI_PROTSTS [1]) and, if enabled, leads to transmit start
interrupt.
Transmit end interrupt event to indicate that a data word transmission has been done:
A transmit end interrupt event occurs when the current transmit data in shift register had
finished. It is indicated by flag TXENDIF (USCI_PROTSTS [2]) and, if enabled, leads to
transmit end interrupt. This event also indicates when the shift control settings (word length,
shift direction, etc.) are internally “frozen” for the current data word transmission. In UART
and I
2
C mode, the transmit data valid is according to TXEMPTY (USCI_BUFSTS [8]) and
protocol relative internal signal with the transmit end interrupt event.
Receiver start event to indicate that a data word reception has started:
When the receive clock edge that shifts in the first bit of a new data word is detected and
reception is enabled, a receiver start event occurs. It is indicated by flag RXSTIF
(USCI_PROTSTS [3]) and, if enabled, leads to receiver start interrupt.
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