PIC16C74B-20/P Microchip Technology Inc., PIC16C74B-20/P Datasheet - Page 98
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PIC16C74B-20/P
Manufacturer Part Number
PIC16C74B-20/P
Description
40 PIN, 7 KB OTP, 192 RAM, 33 I/O
Manufacturer
Microchip Technology Inc.
Datasheet
1.PIC16C74B-20P.pdf
(184 pages)
Specifications of PIC16C74B-20/P
A/d Inputs
8-Channel, 8-Bit
Cpu Speed
5 MIPS
Eeprom Memory
0 Bytes
Input Output
33
Interface
I2C/SPI/USART
Memory Type
OTP
Number Of Bits
8
Package Type
40-pin PDIP
Programmable Memory
7K Bytes
Ram Size
192 Bytes
Speed
4 MHz
Timers
2-8-bit, 1-16-bit
Voltage, Range
2.5-5.5 V
Lead Free Status / Rohs Status
RoHS Compliant part
Electrostatic Device
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PIC16C63A/65B/73B/74B
FIGURE 13-7:
13.9
If the code protection bit(s) have not been pro-
grammed, the on-chip program memory can be read
out for verification purposes.
13.10 ID Locations
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.
13.11
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
voltage. This allows customers to manufacture boards
with unprogrammed devices, and then program the
microcontroller just before shipping the product. This
also allows the most recent firmware or a custom firm-
ware to be programmed.
DS30605C-page 98
Note:
INSTRUCTION FLOW
Note
INTF Flag
(INTCON<1>)
GIE bit
(INTCON<7>)
Instruction
Fetched
Instruction
Executed
CLKOUT
INT pin
OSC1
Program Verification/Code
Protection
1:
2:
3:
4:
PC
In-Circuit Serial Programming
(4)
Microchip does not recommend code pro-
tecting windowed devices. Devices that
are code protected may be erased, but not
programmed again.
XT, HS or LP 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.
OST
Inst(PC) = SLEEP
Q1 Q2 Q3 Q4
Inst(PC - 1)
= 1024Tosc (drawing not to scale). This delay is not present in RC osc mode.
PC
WAKE-UP FROM SLEEP THROUGH INTERRUPT
Q1 Q2 Q3 Q4
Inst(PC + 1)
SLEEP
PC+1
Q1
Processor in
SLEEP
PC+2
T
OST (2)
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.
Depending on the command, 14 bits of program data are
then supplied to or from the device, depending if the
command was a load or a read. For complete details of
serial programming, please refer to the PIC16C6X/7X
Programming Specifications (Literature #DS30228).
FIGURE 13-8:
PC+2
External
Connector
Signals
Data I/O
CLK
+5V
V
0V
PP
PP
Interrupt Latency
Dummy cycle
) pin from V
PC + 2
(2)
TYPICAL IN-CIRCUIT
SERIAL PROGRAMMING
CONNECTION
To Normal
Connections
To Normal
Connections
Q1 Q2 Q3 Q4
IL
2000 Microchip Technology Inc.
Inst(0004h)
Dummy cycle
to V
0004h
IHH
(see programming
V
V
MCLR/V
RB6
RB7
Q1 Q2 Q3 Q4
DD
SS
PIC16CXX
Inst(0005h)
Inst(0004h)
0005h
V
PP
DD