PIC16LF819T-E/SO Microchip Technology, PIC16LF819T-E/SO Datasheet - Page 169

• Manufacturer Part Number: PIC16LF819T-E/SO
• Description: IC PIC MCU FLASH 2KX14 18SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16LF819T-E/SO

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 10MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Program Memory Size: 3.5KB (2K x 14)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 18-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification

15.2.4
During Sleep mode, all clocks to the EUSART are
suspended. Therefore, the Baud Rate Generator is
inactive and proper byte reception cannot be
performed. The auto-wake-up feature allows the
controller to wake-up due to activity on the RX/DT line
while the EUSART is operating in Asynchronous mode.
The auto-wake-up feature is enabled by setting the
WUE bit (BAUDCON<1>). Once set, the typical receive
sequence on RX/DT is disabled and the EUSART
remains in an Idle state, monitoring for a wake-up event
independent of the CPU mode. A wake-up event
consists of a high-to-low transition on the RX/DT line.
(This coincides with the start of a Sync Break or a
Wake-up Signal character for the LIN protocol.)
Following a wake-up event, the module generates an
RCIF interrupt. The interrupt is generated synchro-
nously to the Q clocks in normal operating modes
(Figure 15-8) and asynchronously if the device is in
Sleep mode (Figure 15-9). The interrupt condition is
cleared by reading the RCREG register.
The WUE bit is automatically cleared once a low-to-high
transition is observed on the RX line following the wake-
up event. At this point, the EUSART module is in Idle
mode and returns to normal operation. This signals to
the user that the Sync Break event is over.
15.2.4.1
Since auto-wake-up functions by sensing rising edge
transitions on RX/DT, information with any state changes
before the Stop bit may signal a false End-of-Character
FIGURE 15-8:
FIGURE 15-9:
© 2008 Microchip Technology Inc.
Note 1: The EUSART remains in Idle while the WUE bit is set.
RX/DT Line
Note 1:
RX/DT Line
WUE bit
WUE bit
OSC1
2:
OSC1
RCIF
RCIF
(1)
(2)
If the wake-up event requires long oscillator warm-up time, the auto-clear of the WUE bit can occur while the stposc signal is still active.
This sequence should not depend on the presence of Q clocks.
The EUSART remains in Idle while the WUE bit is set.
AUTO-WAKE-UP ON SYNC BREAK
CHARACTER
Special Considerations Using
Auto-Wake-up
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Bit set by user
Bit set by user
Sleep Command Executed
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING NORMAL OPERATION
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP
Q1
Sleep Ends
(EOC) and cause data or framing errors. To work prop-
erly, therefore, the initial character in the transmission
must be all ‘0’s. This can be 00h (8 bits) for standard
RS-232 devices or 000h (12 bits) for LIN bus.
Oscillator start-up time must also be considered,
especially in applications using oscillators with longer
start-up intervals (i.e., XT or HS mode). The Sync
Break (or Wake-up Signal) character must be of
sufficient length and be followed by a sufficient interval
to allow enough time for the selected oscillator to start
and provide proper initialization of the EUSART.
15.2.4.2
The timing of WUE and RCIF events may cause some
confusion when it comes to determining the validity of
received data. As noted, setting the WUE bit places the
EUSART in an Idle mode. The wake-up event causes
a receive interrupt by setting the RCIF bit. The WUE bit
is cleared after this when a rising edge is seen on RX/
DT. The interrupt condition is then cleared by reading
the RCREG register. Ordinarily, the data in RCREG will
be dummy data and should be discarded.
The fact that the WUE bit has been cleared (or is still
set) and the RCIF flag is set should not be used as an
indicator of the integrity of the data in RCREG. Users
should consider implementing a parallel method in
firmware to verify received data integrity.
To assure that no actual data is lost, check the RCIDL
bit to verify that a receive operation is not in process. If
a receive operation is not occurring, the WUE bit may
then be set just prior to entering the Sleep mode.
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
PIC18F2450/4450
Cleared due to user read of RCREG
Cleared due to user read of RCREG
Special Considerations Using
the WUE Bit
Note 1
DS39760D-page 167
Auto-Cleared
Auto-Cleared