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
Programming Considerations
Within the user program, one of the first things to consider is port initialisation. After a reset, all of
the I/O data and port control registers will be set high. This means that all I/O pins will default to
an input state, the level of which depends on the other connected circuitry and whether pull-high
selections have been chosen. If the port control registers, PAC~PDC, are then programmed to setup
some pins as outputs, these output pins will have an initial high output value unless the associated
port data registers, PA~PD, are first programmed. Selecting which pins are inputs and which are
outputs can be achieved byte-wide by loading the correct values into the appropriate port control
register or by programming individual bits in the port control register using the “SET [m].i” and
“CLR [m].i” instructions. Note that when using these bit control instructions, a read-modify-write
operation takes place. The microcontroller must first read in the data on the entire port, modify it to
the required new bit values and then rewrite this data back to the output ports.
Port A has the additional capability of providing wake-up functions. When the device is in the
SLEEP or IDLE Mode, various methods are available to wake the device up. One of these is a high
to low transition of any of the Port A pins. Single or multiple pins on Port A can be setup to have this
function.
Timer Modules – TM
One of the most fundamental functions in any microcontroller device is the ability to control and
measure time. To implement time related functions each device includes several Timer Modules,
abbreviated to the name TM. The TMs are multi-purpose timing units and serve to provide
operations such as Timer/Counter, Input Capture, Compare Match Output and Single Pulse Output
as well as being the functional unit for the generation of PWM signals. Each of the TMs has either
two or three individual interrupts. The addition of input and output pins for each TM ensures that
users are provided with timing units with a wide and flexible range of features.
The common features of the different TM types are described here with more detailed information
provided in the individual Compact, Standard and Enhanced TM sections.
Introduction
The devices contain up to two TMs with each TM having a reference name of TM0 and TM1. Each
individual TM can be categorised as a certain type, namely Compact Type TM (CTM), Standard
Type TM (STM) or Enhanced Type TM (ETM). Although similar in nature, the different TM types
vary in their feature complexity. The common features to all of the Compact, Standard and Enhanced
TMs will be described in this section and the detailed operation regarding each of the TM types will
be described in separate sections. The main features and differences between the three types of TMs
are summarised in the accompanying table.
Function
CTM
STM
ETM
Timer/Counter
√
√
√
I/P Capture
—
√
√
Compare Match Output
√
√
√
PWM Channels
1
1
2
Single Pulse Output
—
1
2
PWM Alignment
Edge
Edge
Edge & Centre
PWM Adjustment Period & Duty Duty or Period
Duty or Period
Duty or Period
TM Function Summary
Rev. 1.10
66
March 25, 2013
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