PIC16F628A-I/ML Microchip Technology, PIC16F628A-I/ML Datasheet - Page 30

• Manufacturer Part Number: PIC16F628A-I/ML
• Description: IC MCU FLASH 2KX14 EEPROM 28QFN
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F628A-I/ML

• Core Size: 8-Bit
• Program Memory Size: 3.5KB (2K x 14)
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 224 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Controller Family/series: PIC16F
• No. Of I/o's: 16
• Eeprom Memory Size: 128Byte
• Ram Memory Size: 224Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 224 B
• Interface Type: SCI, USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 16
• Number Of Timers: 1 x 16 bit
• 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, DM164120-4
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AC164324 - MODULE SKT FOR MPLAB 8DFN/16QFNXLT28QFN3 - SOCKET TRAN ICE 18DIP/28QFNI3DBF648 - BOARD DAUGHTER ICEPIC3AC164033 - ADAPTER 28QFN TO 18DIPAC162053 - HEADER INTERFACE ICD,ICD2 18DIPDV007003 - PROGRAMMER UNIVERSAL PROMATE II
• Data Converters: -
• Lead Free Status / Rohs Status: Details

PIC16F627A/628A/648A
4.3
The Program Counter (PC) is 13-bits wide. The low
byte comes from the PCL register, which is a readable
and writable register. The high byte (PC<12:8>) is not
directly readable or writable and comes from PCLATH.
On any Reset, the PC is cleared. Figure 4-4 shows the
two situations for loading the PC. The upper example
in Figure 4-4 shows how the PC is loaded on a write to
PCL (PCLATH<4:0> → PCH). The lower example in
Figure 4-4 shows how the PC is loaded during a CALL
or GOTO instruction (PCLATH<4:3> → PCH).
FIGURE 4-4:
4.3.1
A computed GOTO is accomplished by adding an offset
to the program counter (ADDWF PCL). When doing a
table read using a computed GOTO method, care
should be exercised if the table location crosses a PCL
memory boundary (each 256-byte block). Refer to the
Application Note AN556 “Implementing a Table Read”
(DS00556).
4.3.2
The PIC16F627A/628A/648A family has an 8-level
deep x 13-bit wide hardware stack (Figure 4-1). The
stack space is not part of either program or data space
and the Stack Pointer is not readable or writable. The
PC is PUSHed onto the stack when a CALL instruction
is executed or an interrupt causes a branch. The stack
is POPed in the event of a RETURN,
RETFIE instruction execution. PCLATH is not affected
by a PUSH or POP operation.
DS40044G-page 30
PC
PC
12
12 11 10
2
PCL and PCLATH
PCH
5
PCLATH<4:3>
PCH
COMPUTED GOTO
STACK
PCLATH
PCLATH<4:0>
8
PCLATH
8
7
7
LOADING OF PC IN
DIFFERENT SITUATIONS
PCL
PCL
11
8
0
0
Instruction with
PCL as
Destination
ALU result
GOTO, CALL
Opcode <10:0>
RETLW or a
The stack operates as a circular buffer. This means that
after the stack has been PUSHed eight times, the ninth
PUSH overwrites the value that was stored from the
first PUSH. The tenth PUSH overwrites the second
PUSH (and so on).
4.4
The INDF register is not a physical register. Addressing
the INDF register will cause indirect addressing.
Indirect addressing is possible by using the INDF
register. Any instruction using the INDF register
actually accesses data pointed to by the File Select
Register (FSR). Reading INDF itself indirectly will
produce 00h. Writing to the INDF register indirectly
results in a no-operation (although Status bits may be
affected). An effective 9-bit address is obtained by
concatenating the 8-bit FSR register and the IRP bit
(STATUS<7>), as shown in Figure 4-5.
A simple program to clear RAM location 20h-2Fh using
indirect addressing is shown in Example 4-1.
EXAMPLE 4-1:
NEXT
Note 1: There are no Status bits to indicate stack
2: There are no instructions/mnemonics
Indirect Addressing, INDF and
FSR Registers
MOVLW
MOVWF
CLRF
INCF
BTFSS
GOTO
overflow or stack underflow conditions.
called PUSH or POP. These are actions
that occur from the execution of the
CALL, RETURN, RETLW and RETFIE
instructions, or the vectoring to an
interrupt address.
0x20
FSR
INDF
FSR
FSR,4
NEXT
INDIRECT ADDRESSING
© 2009 Microchip Technology Inc.
;initialize pointer
;to RAM
;clear INDF register
;inc pointer
;all done?
;no clear next
;yes continue