In Circ�It Programming - Holtek HT68F Series Manual

In Circuit Programming
The provision of Flash type Program Memory provides the user with a means of convenient and
easy upgrades and modifications to their programs on the same device.
As an additional convenience, Holtek has provided a means of programming the microcontroller
in-circuit using a 5-pin interface. This provides manufacturers with the possibility of manufacturing
their circuit boards complete with a programmed or un-programmed microcontroller, and then
programming or upgrading the program at a later stage. This enables product manufacturers to easily
keep their manufactured products supplied with the latest program releases without removal and
re-insertion of the device.
The Program Memory and EEPROM data memory can both be programmed serially in-circuit using
this 5-wire interface. Data is downloaded and uploaded serially on a single pin with an additional
line for the clock. Two additional lines are required for the power supply and one line for the reset.
The technical details regarding the in-circuit programming of the devices are beyond the scope of
this document and will be supplied in supplementary literature.
During the programming process the RES pin will be held low by the programmer disabling the
normal operation of the microcontroller and taking control of the PA0 and PA2 I/O pins for data
and clock programming purposes. The user must there take care to ensure that no other outputs are
connected to these two pins.
Note: * may be resistor or capacitor. The resistance of * must be greater than 1kΩ or the capacitance
of * must be less than 1nF.
Rev. 2.10
HT68F20/HT68F30/HT68F40/HT68F50/HT68F60
HT68FU30/HT68FU40/HT68FU50/HT68FU60
Enhanced I/O Flash Type 8-Bit MCU with EEPROM
MCU Programming Pins
PA0 Seria� Data Inp�t/O�tp�t
PA2 Seria� C�ock
RES Device Reset
VDD Power S�pp��
VSS Gro�nd
W r i t e r C o n n e c t o r
S i g n a l s
W r i t e r _ V D D
R E S
D A T A
C L K
W r i t e r _ V S S
* *
T o o t h e r C i r c u i t
Programmer Pin
RES
DATA
CLK
Programmer and MCU Pins
32
Function
M C U P r o g r a m m i n g
P i n s
V D D
R E S
D A T A
C L K
V S S
*
MCU Pins
PB0
PA0
PA2
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