PIC17C752-08/CL MICROCHIP [Microchip Technology], PIC17C752-08/CL Datasheet - Page 194

• Manufacturer Part Number: PIC17C752-08/CL
• Description: High-Performance 8-Bit CMOS EPROM Microcontrollers with 10-bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

PIC17C7XX
17.6
The PIC17C7XX group of the high end family
(PIC17CXXX) has an added feature that allows serial
programming 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.
“special” variants of the product may be offered, and
code updates are possible. This allows for increased
design flexibility.
To place the device into the serial programming test
mode, two pins will need to be placed at V
are the TEST pin and the MCLR/V
sequence of events must occur as follows:
1.
2.
There is a setup time between step 1 and step 2 that
must be met.
After this sequence the Program Counter is pointing to
program memory address 0xFF60. This location is in
the Boot ROM. The code initializes the USART/SCI so
that it can receive commands. For this, the device must
be clocked. The device clock source in this mode is the
RA1/T0CKI pin. After delaying to allow the USART/SCI
to initialize, commands can be received. The flow is
shown in these 3 steps:
1.
2.
3.
TABLE 17-3:
DS30289A-page 194
Devices may be serialized to make the product unique,
Name
RA4/RX1/DT1
RA5/TX1/CK1
RA1/T0CKI
TEST
MCLR/V
V
V
DD
SS
The TEST pin is placed at V
The MCLR/V
The device clock source starts.
Wait 80 device clocks for Boot ROM code to con-
figure the USART/SCI.
Commands may now be sent.
In-Circuit Serial Programming
PP
PP
ICSP INTERFACE PINS
pin is placed at V
MCLR/V
Function
TEST
OSCI
IHH
V
V
CK
DT
DD
SS
.
IHH
PP
PP
.
pin. Also a
IHH
. These
Type
I/O
P
P
P
I
I
I
During Programming
Description
Serial Data
Serial Clock
Device Clock Source
Test mode selection control input. Force to V
Master Clear reset and Device Programming Voltage
Positive supply for logic and I/O pins
Ground reference for logic and I/O pins
For complete details of serial programming, please
refer to the PIC17C7XX Programming Specification.
(Contact your local Microchip Technology Sales Office
for availability.)
FIGURE 17-4: TYPICAL IN-CIRCUIT SERIAL
TEST CNTL
Data CLK
Dev. CLK
External
Connector
Signals
Data I/O
+5V
V
0V
PP
PROGRAMMING
CONNECTION
To Normal
Connections
To Normal
Connections
1998 Microchip Technology Inc.
TEST
V
V
MCLR/V
RA1/T0CKI
RA4/RX1/DT1
RA5/TX1/CK1
DD
SS
PIC17C7XX
IHH
,
V
PP
DD