HT66F24D View Datasheet(PDF) - Holtek Semiconductor
Part Name
Description
MFG CO.
'HT66F24D' PDF : 177 Pages View PDF
A/D Flash Type 8-bit MCU with EEPROM
HT66F24D/HT66F25D
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.
Holtek Writer Pins
ICPDA
ICPCK
MCU Programming Pins
PA0
PA2
Pin Description
Programming Serial Data
Programming Clock
ICPMS
PB0
Programming Mode Select
VDD
VSS
VDD
VSS
Power Supply
Ground
The Program Memory can 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 ICPMS 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.
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
VDD
VDD
IC P M S
PB0
IC P D A
PA0
IC P C K
PA2
VSS
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 1kΩ or the capacitance of * must be less than 1nF.
Rev. 1.10
24
March 25, 2013
Share Link: 
