Datasheet
Table Of Contents
- High Performance RISC CPU:
- Special Microcontroller Features:
- Low Power Features:
- Peripheral Features:
- Pin Diagrams
- Most Current Data Sheet
- Errata
- Customer Notification System
- 1.0 General Description
- 2.0 PIC16F627A/628A/648A Device Varieties
- 3.0 Architectural Overview
- 4.0 Memory Organization
- FIGURE 4-1: Program Memory Map and Stack
- TABLE 4-1: general purpose STATIC ram Registers
- TABLE 4-2: Access to Banks of Registers
- FIGURE 4-2: Data Memory Map of the PIC16F627A and PIC16F628A
- FIGURE 4-3: Data Memory Map of the PIC16F648A
- TABLE 4-3: Special Registers Summary Bank0
- TABLE 4-4: Special Function Registers Summary Bank1
- TABLE 4-5: Special Function Registers Summary Bank2
- TABLE 4-6: Special Function Registers Summary Bank3
- FIGURE 4-4: Loading Of PC In Different Situations
- FIGURE 4-5: Direct/Indirect Addressing PIC16F627A/628A/648A
- 5.0 I/O Ports
- FIGURE 5-1: Block Diagram of RA0/AN0:RA1/AN1 Pins
- FIGURE 5-2: Block Diagram of RA2/Vref Pin
- FIGURE 5-3: Block Diagram of the RA3/AN3 Pin
- FIGURE 5-4: Block Diagram of RA4/T0CKI Pin
- FIGURE 5-5: Block Diagram of the RA5/MCLR/Vpp Pin
- FIGURE 5-6: Block Diagram of RA6/OSC2/CLKOUT Pin
- FIGURE 5-7: Block Diagram of RA7/OSC1/CLKIN Pin
- TABLE 5-1: PORTA Functions
- TABLE 5-2: Summary of Registers Associated with PORTA(1)
- FIGURE 5-8: Block Diagram of RB0/INT Pin
- FIGURE 5-9: Block Diagram of RB1/RX/DT Pin
- FIGURE 5-10: Block Diagram of RB2/TX/CK Pin
- FIGURE 5-11: Block Diagram of RB3/CCP1 Pin
- FIGURE 5-12: Block Diagram of RB4/PGM Pin
- FIGURE 5-13: Block Diagram of RB5 Pin
- FIGURE 5-14: Block Diagram of RB6/T1OSO/T1CKI Pin
- FIGURE 5-15: Block Diagram of the RB7/T1OSI Pin
- TABLE 5-3: PORTB Functions
- TABLE 5-4: Summary of Registers Associated With PORTB(1)
- FIGURE 5-16: Successive I/O Operation
- 6.0 Timer0 Module
- 7.0 Timer1 Module
- 8.0 Timer2 Module
- 9.0 Capture/Compare/PWM (CCP) Module
- TABLE 9-1: CCP Mode - Timer Resource
- FIGURE 9-1: Capture Mode Operation Block Diagram
- FIGURE 9-2: Compare Mode Operation Block Diagram
- TABLE 9-2: Registers Associated with Capture, compare, and Timer1
- FIGURE 9-3: Simplified PWM Block Diagram
- FIGURE 9-4: PWM OUTPUT
- TABLE 9-3: Example PWM Frequencies and Resolutions at 20 MHz
- TABLE 9-4: Registers Associated with PWM and Timer2
- 10.0 Comparator Module
- 11.0 Voltage Reference Module
- 12.0 Universal Synchronous Asynchronous Receiver Transmitter (USART) Module
- TABLE 12-1: BAUD rATE fORMULA
- TABLE 12-2: Registers Associated with Baud Rate Generator
- TABLE 12-3: Baud Rates for synchronous Mode
- TABLE 12-4: Baud Rates for Asynchronous Mode (BRGH = 0)
- TABLE 12-5: Baud Rates for Asynchronous Mode (BRGH = 1)
- FIGURE 12-1: RX Pin Sampling Scheme. BRGH = 0
- FIGURE 12-2: RX Pin Sampling Scheme, BRGH = 1
- FIGURE 12-3: RX Pin Sampling Scheme, BRGH = 1
- FIGURE 12-4: RX Pin Sampling Scheme, BRGH = 0 OR BRGH = 1
- FIGURE 12-5: USART Transmit Block Diagram
- FIGURE 12-6: Asynchronous Transmission
- FIGURE 12-7: Asynchronous Transmission (Back to Back)
- TABLE 12-6: Registers Associated with Asynchronous Transmission
- FIGURE 12-8: USART Receive Block Diagram
- FIGURE 12-9: Asynchronous Reception with Address Detect
- FIGURE 12-10: Asynchronous Reception with Address Byte First
- FIGURE 12-11: Asynchronous Reception with Address Byte First Followed by Valid Data Byte
- TABLE 12-7: Registers Associated with Asynchronous Reception
- TABLE 12-8: Registers Associated with Asynchronous Reception
- TABLE 12-9: Registers Associated with Synchronous Master Transmission
- FIGURE 12-12: Synchronous Transmission
- FIGURE 12-13: Synchronous Transmission (Through TXEN)
- TABLE 12-10: Registers Associated with Synchronous Master Reception
- FIGURE 12-14: Synchronous Reception (Master Mode, SREN)
- TABLE 12-11: Registers Associated with Synchronous Slave Transmission
- TABLE 12-12: Registers Associated with Synchronous Slave Reception
- 13.0 Data EEPROM Memory
- 14.0 Special Features of the CPU
- FIGURE 14-1: Crystal Operation (or Ceramic Resonator) (HS, XT or LP Osc Configuration)
- TABLE 14-1: Capacitor Selection for Ceramic Resonators
- TABLE 14-2: Capacitor Selection for Crystal Oscillator
- FIGURE 14-2: External Parallel Resonant Crystal Oscillator Circuit
- FIGURE 14-3: External Series Resonant Crystal Oscillator Circuit
- FIGURE 14-4: External Clock Input Operation (EC, HS, XT or LP Osc Configuration)
- FIGURE 14-5: RC OSCILLATOR MODE
- FIGURE 14-6: Simplified Block Diagram of On-chip Reset Circuit
- FIGURE 14-7: Brown-out Situations WITH PWRT ENABLED
- TABLE 14-3: Time out in Various Situations
- TABLE 14-4: Status/PCON Bits and Their Significance
- TABLE 14-5: Summary of Registers Associated with Brown-out Reset
- TABLE 14-6: Initialization Condition for Special Registers
- TABLE 14-7: Initialization Condition for Registers
- FIGURE 14-8: Time out Sequence on Power-up (MCLR not tied to Vdd): Case
- FIGURE 14-9: Time out Sequence on Power-up (MCLR not tied to Vdd): Case 2
- FIGURE 14-10: Time out Sequence on Power-up (MCLR tied to Vdd)
- FIGURE 14-11: External Power-on Reset Circuit (For Slow Vdd Power-up)
- FIGURE 14-12: External Brown-out Protection Circuit 1
- FIGURE 14-13: External Brown-out Protection Circuit 2
- FIGURE 14-14: Interrupt Logic
- FIGURE 14-15: INT Pin Interrupt Timing
- TABLE 14-8: Summary of interrupt registers
- FIGURE 14-16: Watchdog Timer Block Diagram
- TABLE 14-9: Summary of Watchdog Timer Registers
- FIGURE 14-17: Wake-up from Sleep Through Interrupt
- FIGURE 14-18: Typical In-Circuit Serial Programming Connection
- 15.0 Instruction Set Summary
- 16.0 Development Support
- 17.0 Electrical Specifications
- FIGURE 17-1: PIC16F627A/628A/648A VOLTAGE-FREQUENCY GRAPH, -40°C £ TA £ +125°C
- FIGURE 17-2: PIC16LF627A/628A/648A VOLTAGE-FREQUENCY GRAPH, -40°C £ TA £ +85°C
- TABLE 17-1: DC Characteristics: PIC16F627A/628A/648A (Industrial, Extended) PIC16LF627A/628A/648A...
- TABLE 17-2: Comparator Specifications
- TABLE 17-3: Voltage Reference Specifications
- FIGURE 17-3: Load Conditions
- FIGURE 17-4: External Clock Timing
- TABLE 17-4: External Clock Timing Requirements
- TABLE 17-5: pRECISION INTERNAL OSCILLATOR Parameters
- FIGURE 17-5: CLKOUT and I/O Timing
- TABLE 17-6: CLKOUT and I/O Timing Requirements
- FIGURE 17-6: Reset, Watchdog Timer, Oscillator Start-Up Timer and Power-Up Timer Timing
- FIGURE 17-7: Brown-out Detect Timing
- TABLE 17-7: Reset, Watchdog Timer, Oscillator Start-up Timer and Power-up Timer Requirements
- FIGURE 17-8: Timer0 and Timer1 External Clock Timings
- TABLE 17-9: Timer0 and Timer1 External Clock Requirements
- FIGURE 17-10: Capture/Compare/PWM Timings
- TABLE 17-8: Capture/Compare/PWM Requirements
- FIGURE 17-11: TIMER0 Clock Timing
- TABLE 17-9: TIMER0 Clock Requirements
- 18.0 DC and AC Characteristics Graphs and Tables
- 19.0 Packaging Information
- Appendix A: Data Sheet Revision History
- Appendix B: Device Differences
- Appendix C: Device Migrations
- Appendix D: Migrating from other PICmicro Devices
- Appendix E: Development Tool Version Requirements
- Index
- Product ID System
- Worldwide Sales
2002 Microchip Technology Inc. Preliminary DS40044A-page 71
PIC16F627A/628A/648A
12.1 USART Baud Rate Generator
(BRG)
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 12-1 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
OSC, the nearest
integer value for the SPBRG register can be calculated
using the formula in Table 12-1. From this, the error in
baud rate can be determined.
Example 12-1 shows the calculation of the baud rate
error for the following conditions:
F
OSC = 16 MHz
Desired Baud Rate = 9600
BRGH = 0
SYNC = 0
EXAMPLE 12-1: CALCULATING BAUD
RATE ERROR
It may be advantageous to use the high baud rate
(BRGH = 1) even for slower baud clocks. This is
because the F
OSC/(16(X + 1)) equation can reduce the
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 output-
ting the new baud rate.
TABLE 12-1: BAUD RATE FORMULA
TABLE 12-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Desired Baud Rate
Fosc
64 x 1+()
-----------------------
=
9600
16000000
64 x 1+()
------------------------
=
x 25.042=
Calculated Baud Rate
16000000
64 25 1+()
--------------------------
9615==
Error
(Calculated Baud Rate - Desired Baud Rate)
Desired Baud Rate
----------------------------------------------------------------------------------------------------------
=
=
9615 9600–
9600
------------------------------
0.16%=
SYNC BRGH = 0 (Low Speed) BRGH = 1 (High Speed)
0
1
(Asynchronous) Baud Rate = FOSC/(64(X+1))
(Synchronous) Baud Rate = F
OSC/(4(X+1))
Baud Rate= F
OSC/(16(X+1))
NA
Legend: X = value in SPBRG (0 to 255)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on
POR
Value on all
other
RESETS
98h TXSTA CSRC TX9 TXEN SYNC —BRGHTRMT TX9D 0000 -010 0000 -010
18h RCSTA SPEN
RX9 SREN CREN ADEN FERR OERR RX9D 0000 000x 0000 000x
99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unknown, - = unimplemented read as '0'.
Shaded cells are not used by the BRG.