PIC16C745/P Microchip Technology, PIC16C745/P Datasheet - Page 108

• Manufacturer Part Number: PIC16C745/P
• Description: 8-Bit CMOS Microcontrollers with USB
• Manufacturer: Microchip Technology

PIC16C745/765
FIGURE 13-8: WAKE-UP FROM SLEEP THROUGH INTERRUPT
13.10
If the code protection bit(s) have not been pro-
grammed, the on-chip program memory can be read
out for verification purposes.
13.11
Four memory locations (2000h - 2003h) are designated
as ID locations where the user can store checksum or
other code-identification numbers. These locations are
not accessible during normal execution but are read-
able and writable during program/verify. It is recom-
mended that only the four least significant bits of the ID
location are used.
13.12
PIC16CXX microcontrollers can be serially pro-
grammed while in the end application circuit. This is
simply done with two lines for clock and data, and three
other lines for power, ground and the programming volt-
age. This allows customers to manufacture boards with
unprogrammed devices, and then program the micro-
controller just before shipping the product. This also
allows the most recent firmware or a custom firmware
to be programmed.
DS41124A-page 108
Note 1:
GIE bit
(INTCON<7>)
Note:
INTF flag
(INTCON<1>)
INSTRUCTION FLOW
Instruction
fetched
Instruction
executed
CLKOUT
INT pin
2:
3:
4:
OSC1
Program Verification/Code Protection
ID Locations
In-Circuit Serial Programming
PC
HS oscillator mode assumed.
T
GIE = ’1’ assumed. After wake- up, the processor jumps to the interrupt routine. If GIE = ’0’, execution will continue in-line.
CLKOUT is not available in these osc modes, but shown here for timing reference.
(4)
Microchip does not recommend code pro-
tecting windowed devices. Devices that are
code protected may be erased, but not pro-
grammed again.
OST
Inst(PC) = SLEEP
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1
= 1024T
Inst(PC - 1)
PC
OSC
(drawing not to scale). This delay is not present in EC osc mode.
Inst(PC + 1)
SLEEP
PC+1
Processor in
Advanced Information
SLEEP
PC+2
Tost
(2)
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Inst(PC + 2)
Inst(PC + 1)
The device is placed into a program/verify mode by
holding the RB6 and RB7 pins low, while raising the
MCLR (V
specification). RB6 becomes the programming clock
and RB7 becomes the programming data. Both RB6
and RB7 are Schmitt Trigger inputs in this mode.
After reset, to place the device into programming/verify
mode, the program counter (PC) is at location 00h. A
6-bit command is then supplied to the device. Depend-
ing on the command, 14 bits of program data are then
supplied to or from the device, depending if the com-
mand was a load or a read. For complete details of
serial programming, please refer to the PIC16C6X/7X
Programming Specifications (Literature #DS30228).
FIGURE 13-9: TYPICAL IN-CIRCUIT SERIAL
PC+2
External
Connector
Signals
Data I/O
Interrupt Latency
CLK
+5V
V
0V
PP
PP
Dummy cycle
) pin from V
PC + 2
PROGRAMMING
CONNECTION
(2)
To Normal
Connections
To Normal
Connections
IL
1999 Microchip Technology Inc.
Inst(0004h)
Dummy cycle
to V
0004h
IHH
(see programming
V
V
MCLR/V
RB6
RB7
DD
SS
PIC16CXX
Inst(0005h)
Inst(0004h)
0005h
V
PP
DD