PIC16F87-I/SS Microchip Technology, PIC16F87-I/SS Datasheet - Page 101

• Manufacturer Part Number: PIC16F87-I/SS
• Description: IC MCU FLASH 4KX14 EEPROM 20SSOP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F87-I/SS

• Program Memory Type: FLASH
• Program Memory Size: 7KB (4K x 14)
• Package / Case: 20-SSOP
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Eeprom Size: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 368 B
• Interface Type: SSP/USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 16
• Number Of Timers: 3
• 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
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM163014
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT20SS-1 - SOCKET TRANSITION 18DIP 20SSOPAC164307 - MODULE SKT FOR PM3 28SSOP
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

11.1
The BRG supports both the Asynchronous and Syn-
chronous modes of the USART. It is a dedicated 8-bit
baud rate generator. The SPBRG register controls the
period of a free-running 8-bit timer. In Asynchronous
mode, bit BRGH (TXSTA<2>) also controls the baud
rate. In Synchronous mode, bit BRGH is ignored.
Table 11-1 shows the formula for computation of the
baud rate for different USART modes, which only apply
in Master mode (internal clock).
Given the desired baud rate and F
integer value for the SPBRG register can be calculated
using the formula in Table 11-1. From this, the error in
baud rate can be determined.
It may be advantageous to use the high baud rate
(BRGH = 1) even for slower baud clocks. This is
because the F
baud rate error in some cases.
Writing a new value to the SPBRG register causes the
BRG timer to be reset (or cleared). This ensures the
BRG does not wait for a timer overflow before
outputting the new baud rate.
TABLE 11-1:
TABLE 11-2:
 2003 Microchip Technology Inc.
Legend: X = value in SPBRG (0 to 255)
98h
18h
99h
Legend:
Address
SYNC
0
1
USART Baud Rate Generator
(BRG)
x = unknown, - = unimplemented, read as ‘0’. Shaded cells are not used by the BRG.
TXSTA
RCSTA
SPBRG
Name
OSC
(Asynchronous) Baud Rate = F
(Synchronous) Baud Rate = F
/(16(X + 1)) equation can reduce the
BAUD RATE FORMULA
REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Baud Rate Generator Register
CSRC
SPEN
Bit 7
BRGH = 0 (Low-speed)
Bit 6
RX9
TX9
OSC
SREN
TXEN
Bit 5
, the nearest
OSC
OSC
CREN
SYNC
Bit 4
Preliminary
/(64(X + 1))
/(4(X + 1))
ADDEN
Bit 3
—
11.1.1
The PIC16F87/88 has an 8 MHz INTRC that can be
used as the system clock, thereby eliminating the need
for external components to provide the clock source.
When the INTRC provides the system clock, the
USART module will also use the INTRC as its system
clock. Table 11-1 shows some of the INTRC fre-
quencies that can be used to generate the USART’s
baud rate.
11.1.2
The system clock is used to generate the desired baud
rate; however, when a low-power mode is entered, the
low-power clock source may be operating at a different
frequency than in full power execution. In SLEEP
mode, no clocks are present. This may require the
value in SPBRG to be adjusted.
11.1.3
The data on the RB2/SDO/RX/DT pin is sampled three
times by a majority detect circuit to determine if a high
or a low level is present at the RX pin.
BRGH
FERR
Bit 2
USART AND INTRC OPERATION
LOW-POWER MODE OPERATION
SAMPLING
OERR
TRMT
Baud Rate = F
Bit 1
BRGH = 1 (High-speed)
RX9D
TX9D
PIC16F87/88
Bit 0
N/A
OSC
0000 -010
0000 000x
0000 0000
POR, BOR
Value on:
/(16(X + 1))
DS30487B-page 99
0000 -010
0000 000x
0000 0000
Value on
RESETS
all other