HT16L21
Pin Description
Pin Name
Type
Serial data input/output pin
Description
SDA/DIO
●
Serial data (SDA) input/output for 2-wire I
2
C interface is an NMOS
open drain structure.
I/O
●
Serial data (DIO) input/output for 3-wire SPI interface is a CMOS
input/output structure.
Serial clock input pin
I
I
SCL/CLK
CSB
●
Serial data (SCL) is clock input for 2-wire I
2
C interface.
●
Serial data (CLK) is clock input for 3-wire SPI interface
Chip select pin
This pin is available for 3-wire SPI interface and not used for I
2
C interface.
Communication interface select pin
This pin is used to select the communication interface. When this pin is
connected to V
DD
, the device communicates with MCU or microprocessors
via a 2-wire I
2
C interface. When this pin is connected to V
SS
, the device
communicates with MCU or microprocessors using a 3-wire SPI interface.
LCD common outputs
LCD segment outputs
LCD segment/LED multiplexed driver outputs
Reset input pin
1. This pin is used to initialize all the internal registers and the commands pin.
2. If use internal power on reset circuit only, the RSTB pin must be connected
to V
DD
.
Positive power supply
Negative power supply, ground.
LCD power supply pin
IFS
I
COM0~COM3
SEG0~SEG23
SEG24/LED7~SEG31/LED0
RSTB
VDD
VSS
VLCD
O
O
O
I
—
—
—
Approximate Internal Connections
SCL, SDA (for schmit Trigger type)
COM0~COM4; SEG0~SEG31
DIO (for Schmitt trigger type)
VDD
Vselect-on
Vselect-off
VSS
VSS
IFS, RSTB
LED0~7
CSB, CLK (for schmit Trigger type)
VDD
VDD
VSS
VSS
VSS
Rev. 1.10
3
December 27, 2011
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
