PIC18F2431-I/SO Microchip Technology, PIC18F2431-I/SO Datasheet - Page 225

• Manufacturer Part Number: PIC18F2431-I/SO
• Description: IC PIC MCU FLASH 8KX16 28SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2431-I/SO

• Program Memory Type: FLASH
• Program Memory Size: 16KB (8K x 16)
• Package / Case: 28-SOIC (7.5mm Width)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, Power Control PWM, QEI, POR, PWM, WDT
• Number Of I /o: 24
• Eeprom Size: 256 x 8
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 768 B
• Interface Type: EUSART/I2C/SPI/SSP
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 24
• Number Of Timers: 4
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, ICE4000, DM183021, DV164136
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 5-ch x 10-bit
• Package: 28SOIC W
• Device Core: PIC
• Family Name: PIC18
• Maximum Speed: 40 MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT28SO-1 - SOCKET TRANSITION 28SOIC 300MILI3-DB18F4431 - BOARD DAUGHTER ICEPIC3
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

20.2.3
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
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 RX signal, the RX 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 Detect
must receive a byte with the value of 55h (ASCII “U”,
which is also the LIN/J2602 bus Sync character) in
order to calculate the proper bit rate. The measurement
takes 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 SPBRG begins
counting up, using the preselected clock source on the
first rising edge of RX. After eight bits on the RX pin, or
the fifth rising edge, an accumulated value totalling the
proper BRG period is left in the SPBRGH:SPBRG
registers. Once the 5th edge is seen (should
correspond to the Stop bit), the ABDEN bit is
automatically cleared.
While calibrating the baud rate period, the BRG regis-
ters are clocked at 1/8th the preconfigured clock rate.
The BRG clock can be configured by the BRG16 and
BRGH bits. The BRG16 bit must be set to use both
SPBRG and SPBRGH as a 16-bit counter.
FIGURE 20-1:
 2010 Microchip Technology Inc.
BRG Clock
BRG Value
Note 1:
ABDEN bit
(Interrupt)
SPBRGH
RCIF bit
RCREG
SPBRG
RX Pin
20-1) begins whenever a Start bit is received and
Read
AUTO-BAUD RATE DETECT
The ABD sequence requires the EUSART module to be configured in Asynchronous mode and WUE = 0.
Set by user
XXXXh
AUTOMATIC BAUD RATE CALCULATION
0000h
Start
PIC18F2331/2431/4331/4431
Bit 0
XXXXh
XXXXh
Edge #1
Bit 1
Bit 2
Edge #2
This allows the user to verify that no carry occurred for 8-
bit modes by checking for 00h in the SPBRGH register.
Refer to
While the ABD sequence takes place, the EUSART
state machine is held in Idle. The RCIF interrupt is set
once the fifth rising edge on RX is detected. The value
in the RCREG needs to be read to clear the RCIF
interrupt. RCREG content should be discarded.
TABLE 20-4:
BRG16
Note 1: If the WUE bit is set with the ABDEN bit,
Bit 3
0
0
1
1
(1)
Table 20-4
2: It is up to the user to determine that the
3: To maximize baud rate range, setting
Bit 4
Edge #3
BRGH
Auto-Baud Rate Detection will occur on
the byte following the Break character
(see
Sync Break
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.
the BRG16 bit is recommended if the
auto-baud feature is used.
0
1
0
1
Bit 5
Section 20.3.4 “Auto-Wake-up on
BRG COUNTER CLOCK
RATES
for counter clock rates to the BRG.
Bit 6
Edge #4
Character”).
BRG Counter Clock
Bit 7
F
F
F
F
OSC
OSC
OSC
OSC
DS39616D-page 225
Stop Bit
Edge #5
/512
/256
/128
/32
Auto-Cleared
001Ch
1Ch
00h