PIC18F2221-I/SS Microchip Technology, PIC18F2221-I/SS Datasheet - Page 219

IC PIC MCU FLASH 2KX16 28SSOP

PIC18F2221-I/SS

Manufacturer Part Number
PIC18F2221-I/SS
Description
IC PIC MCU FLASH 2KX16 28SSOP
Manufacturer
Microchip Technology
Series
PIC® 18Fr

Specifications of PIC18F2221-I/SS

Core Size
8-Bit
Program Memory Size
4KB (2K x 16)
Core Processor
PIC
Speed
40MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, HLVD, POR, PWM, WDT
Number Of I /o
25
Program Memory Type
FLASH
Eeprom Size
256 x 8
Ram Size
512 x 8
Voltage - Supply (vcc/vdd)
4.2 V ~ 5.5 V
Data Converters
A/D 10x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
28-SSOP
Controller Family/series
PIC18
No. Of I/o's
25
Eeprom Memory Size
256Byte
Ram Memory Size
512Byte
Cpu Speed
40MHz
No. Of Timers
4
Processor Series
PIC18F
Core
PIC
Data Bus Width
8 bit
Data Ram Size
512 B
Interface Type
EUSART, I2C, MSSP, SPI
Maximum Clock Frequency
40 MHz
Number Of Programmable I/os
25
Number Of Timers
4
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, ICE4000, ICE2000, DV164136
Minimum Operating Temperature
- 40 C
On-chip Adc
10 bit, 10 Channel
Package
28SSOP
Device Core
PIC
Family Name
PIC18
Maximum Speed
40 MHz
Operating Supply Voltage
5 V
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
For Use With
AC164307 - MODULE SKT FOR PM3 28SSOP
Lead Free Status / Rohs Status
 Details

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
PIC18F2221-I/SS
Manufacturer:
MICROCHIP/微芯
Quantity:
20 000
19.1.3
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 19-1) begins whenever a Start bit is received
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 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 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 measurement
is taken over both a low and a high bit time in order to
minimize any effects caused by asymmetry of the incom-
ing 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 ris-
ing edge, an accumulated value totalling the proper BRG
period is left in the SPBRGH:SPBRG 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 (BAUDCON<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 (Figure 19-2).
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 SPBRGH
register. Refer to Table 19-4 for counter clock rates to
the BRG.
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. The contents of RCREG should be discarded.
© 2009 Microchip Technology Inc.
AUTO-BAUD RATE DETECT
PIC18F2221/2321/4221/4321 FAMILY
TABLE 19-4:
19.1.3.1
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,
TXREG 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 the baud rate range, it is
BRGH
timing and communication baud rates
feature.
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
must be taken into consideration when
using the Auto-Baud Rate Detection
recommended to set the BRG16 bit if the
auto-baud feature is used.
ABD and EUSART Transmission
0
1
0
1
BRG COUNTER
CLOCK RATES
BRG Counter Clock
F
F
F
F
OSC
OSC
OSC
OSC
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