Chapter 1 Hardware Structure
V1, C1, C2
LCD voltage pump for HT49R50A-1/HT49C50-1.
LCD power supply for HT49C50L.
LCD voltage pump
The 1/4 LCD duty cycle configuration option will de-
termine whether pin COM3/SEG32 is configured as a
SEG32 segment driver or as a common COM3 output
driver for the LCD panel. COM0~COM2 are the LCD
LCD driver outputs for LCD panel segments
OSC1 and OSC2 are connected to an external RC
network or external crystal (determined by configura-
tion option) for the internal system clock. For external
RC system clock operation, OSC2 is an output pin for
1/4 system clock. If an RTC oscillator on pins OSC3
and OSC4 is used as a system clock, then the OSC1
and OSC2 pins should be left floating.
OSC3 and OSC4 are connected to a 32768Hz crystal
to form a Real Time Clock for timing purposes or to
form a system clock.
Schmitt Trigger reset input, active low.
Positive power supply
Negative power supply, ground
1/2, 1/3 or 1/4
Crystal or RC
1. Each pin on PA can be programmed through a configuration option to have a wake-up function.
2. Only pins PA0~PA3 and PC0~PC3 have a pull-high resistor configuration option. These
pull-high options can only be selected if these four pins are configured as NMOS types. If the
pull-high option is selected then it will apply to all four pins, individual pins cannot be selected to
have pull-high resistors. If setup as CMOS outputs the pull-high configuration option is
3. Due to packaging limitations on the 48-pin SSOP package, I/O pins PB6 and PB7, Port C pins
and LCD segment pins SEG0~SEG9 and SEG28~SEG31 are not present.