HT45FH4J Datasheet, PDF (23/129 Pages) Holtek Semiconductor Inc – Emergency Light Flash MCU

HT45FH4J
Emergency Light Flash MCU
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 4-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 Holtek Flash MCU to Writer Programming Pin correspondence table is as follows:
Holtek Write Pins
ICPDA
ICPCK
VDD
VSS
MCU Programming Pins
PA0
PA2
VDD
VSS
Function
Programming Serial Data/Address
Programming Serial Clock
Power Supply
Ground
During the programming process, the user must there take care to ensure that no other outputs are
connected to these two pins.
The Program Memory and EEPROM data memory can both be programmed serially in-circuit using
this 4-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. The technical details
regarding the in-circuit programming of the device are beyond the scope of this document and will
be supplied in supplementary literature.
W r ite r C o n n e c to r
S ig n a ls
M C U P r o g r a m m in g
P in s
W r ite r _ V D D
VDD
IC P D A
PA0
IC P C K
PA2
W r ite r _ V S S
VSS
*
*
T o o th e r C ir c u it
Note: * may be resistor or capacitor. The resistance of * must be greater than 1k or the capacitance
of * must be less than 1nF.
Rev. 1.10
23
December 14, 2016