PIC18LF6310-I/PT Microchip Technology, PIC18LF6310-I/PT Datasheet - Page 224

• Manufacturer Part Number: PIC18LF6310-I/PT
• Description: IC PIC MCU FLASH 4KX16 64TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18LF6310-I/PT

• Core Size: 8-Bit
• Program Memory Size: 8KB (4K x 16)
• Oscillator Type: Internal
• Core Processor: PIC
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Type: FLASH
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TFQFP
• Controller Family/series: PIC18
• No. Of I/o's: 54
• Ram Memory Size: 768Byte
• Cpu Speed: 40MHz
• No. Of Timers: 4
• No. Of Pwm: RoHS Compliant
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PIC18F6310/6410/8310/8410
18.1.3
The Enhanced USART module supports the automatic
detection and calibration of baud rate. This feature is
active only in Asynchronous mode and while the WUE
bit is clear.
The automatic baud rate measurement sequence
(Figure
and the ABDEN bit is set. The calculation is
self-averaging.
In the Auto-Baud Rate Detect (ABD) mode, the clock to
the BRG is reversed. Rather than the BRG clocking the
incoming RX1 signal, the RX1 signal is timing the BRG.
In ABD mode, the internal Baud Rate Generator is
used as a counter to time the bit period of the incoming
serial byte stream.
Once the ABDEN bit is set, the state machine will clear
the BRG and look for a Start bit. The Auto-Baud Rate
Detect must receive a byte with the value, 55h (ASCII
“U”, which is also the LIN/J2602 bus Sync character),
in order to calculate the proper bit rate. The measure-
ment is taken over both a low and a high bit time in
order to minimize any effects caused by asymmetry of
the incoming signal. After a Start bit, the SPBRG1
begins counting up, using the preselected clock source
on the first rising edge of RX1. After eight bits on the
RX1 pin or the fifth rising edge, an accumulated value
totalling the proper BRG period is left in the
SPBRGH1:SPBRG1 register pair. Once the 5th edge is
seen (this should correspond to the Stop bit), the
ABDEN bit is automatically cleared.
If a rollover of the BRG occurs (an overflow from FFFFh
to 0000h), the event is trapped by the ABDOVF status bit
(BAUDCON1<7>). It is set in hardware by BRG rollovers
and can be set or cleared by the user in software. ABD
mode remains active after rollover events and the
ABDEN bit remains set
While calibrating the baud rate period, the BRG
registers are clocked at 1/8th the preconfigured clock
rate. Note that the BRG clock can be configured by the
BRG16 and BRGH bits. The BRG16 bit must be set to
use both SPBRG1 and SPBRGH1 as a 16-bit counter.
This allows the user to verify that no carry occurred for
8-bit modes by checking for 00h in the SPBRGH1
register. Refer to
the BRG.
DS39635C-page 224
18-1) begins whenever a Start bit is received
AUTO-BAUD RATE DETECT
Table 18-4
(Figure
for counter clock rates to
18-2).
While the ABD sequence takes place, the EUSART
state machine is held in Idle. The RC1IF interrupt is set
once the fifth rising edge on RX1 is detected. The value
in the RCREG1 needs to be read to clear the RC1IF
interrupt. The contents of RCREG1 should be
discarded.
TABLE 18-4:
18.1.3.1
Since the BRG clock is reversed during ABD acquisi-
tion, the EUSART transmitter cannot be used during
ABD. This means that whenever the ABDEN bit is set,
TXREG1 cannot be written to. Users should also
ensure that ABDEN does not become set during a
transmit sequence. Failing to do this may result in
unpredictable EUSART operation.
BRG16
Note 1: If the WUE bit is set with the ABDEN bit,
0
0
1
1
2: It is up to the user to determine that the
3: To maximize baud rate range, it is recom-
BRGH
Auto-Baud Rate Detection will occur on
the byte following the Break character.
incoming character baud rate is within the
range of the selected BRG clock source.
Some combinations of oscillator frequency
and EUSART baud rates are not possible
due to bit error rates. Overall system timing
and communication baud rates must be
taken into consideration when using the
Auto-Baud Rate Detection feature.
mended to set the BRG16 bit if the
auto-baud feature is used.
ABD and EUSART Transmission
0
1
0
1
BRG COUNTER CLOCK
RATES
 2010 Microchip Technology Inc.
BRG Counter Clock
F
F
F
F
OSC
OSC
OSC
OSC
/512
/128
/128
/32