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HT1635A/B Wearable Sports Bracelet
LED Display Application
D/N: AN0393E
Introduction
The HT1635A and HT1635B are Holtek display data memory mapping LED driver
devices, whose driving capacity is up to 352 patterns composed of 44 rows and 8
commons. The HT1635A provides a 4-wire serial interface and the HT1635B provides an
2
I
C interface. Both interfaces are used for MCU data communication. Using the HT66F50
as the host MCU, a demo with two HT1635A devices or two HT1535B devices is taken as
an example in this application note to introduce how to use the HT1635A and HT1635B.
Each HT1635A or HT1635B device on the demo drives 8 commons and 42 rows of RGB
LEDs (8×14 RGB LEDs), showing the wearable sports bracelet LED panel display
functions.
Operating Principles
HT1635A and HT1635B Main Features
•
Operating voltage: 2.4V ~ 5.5V
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Integrated 256kHz RC oscillator
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Frame Rate: 100Hz
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Maximum display capacity: 352 patterns (44 rows and 8 commons)
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Up to 88×4 RAM display data storage
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Supports up to 16-level PWM brightness control
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Four blinking modes: Off, 0.5Hz, 1Hz and 2Hz
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COM driving method selectable: NMOS open-drain or PMOS open-drain
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HT1635A provides a 4-wire serial interface, HT1635B provides an I
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Cascade function for extending applications
•
Package: 64-pin LQFP
HT1635A/B Wearable Sports Bracelet LED Display Application
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2
C serial interface
AN0393E
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Table of Contents
Summary of Contents for Holtek HT1635A
- Page 1 C interface. Both interfaces are used for MCU data communication. Using the HT66F50 as the host MCU, a demo with two HT1635A devices or two HT1535B devices is taken as an example in this application note to introduce how to use the HT1635A and HT1635B.
- Page 2 WRB (Write Serial Clock), DATA (Serial Data), RDB (Read Serial Clock) and CSB (Chip Select). The HT1635B is supplied in the same package type as the HT1635A and is basically pin compatible with the HT1635A, with the exception that the HT1635B includes an I...
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Page 3: Com Driving Methods
SYNC pins of the Master Mode1 device to the corresponding pins on the Slave Mode devices. Use the host MCU to control the CSB pin on each HT1635A device to achieve cascade driving. With respect to the HT1635B, which has an I... - Page 4 HT1635A/B Wearable Sports Bracelet LED Display Application After system power is applied, the HT1635A/HT1635B devices will be initialised by an internal power-on reset circuit. The status of the internal circuits after initialisation is as follows. • System oscillator will be off •...
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Page 5: Demo H/W Block Diagram
RGB LED Matrix board and the bottom board is a power control board. These two boards are connected using a pin header. • RGB LED Matrix Two HT1635A devices or two HT1635B devices jointly drive an RGB LED Matrix composed of 8 commons and 28 rows. • Power Supply Circuit The power supply circuit provides three power supply methods, AC power (100~240V power adapter (DC5V, Micro USB interface) and a Li-battery (one 18650). -
Page 6: Application Circuits
Application Circuits Figure 2 RGB LED Matrix Circuit The RGB LED Matrix PCB is available for the HT1635A and HT1635B. Switching between these two devices can be achieved by using several 0Ω resistors, therefore a general device name HT1635 is used in the schematic diagram. -
Page 7: Power Supply Circuits
HT1635A/B Wearable Sports Bracelet LED Display Application 0R/0805 0R/0805 VDD2 F1 1A fuse VDD1 SS54 MCU_VDD SS54 IO_ACIN IO_USBIN ZNR 0.1uF/275VAC MICRO USB 22uF/10V/1206 1000uF/25V 0.1uF AC 2DIP SOCKET 10nF 10nF VOUT FAS10-5-W 22uF/10V/1206 750K 220uF/16V/7343 240K PVOUT 22uF/10V/1206 VBAT... -
Page 8: Dc-Dc Boost Circuit
18650 Li-battery to supply power. Since the operating voltages for the host MCU and the HT1635A/HT1635B are set to 5V, when using the Li-battery to supply power, the DC-DC boost circuit must be used to increase the battery voltage to Each power type is connected with a Schottky diode SS54 to be isolated from the other two power sources. -
Page 9: Li-Battery Charging Circuit
HT1635A/B Wearable Sports Bracelet LED Display Application Li-battery Charging Circuit IO_CHG_DET STAT ISET BATT APL3202-SOT23-5 IO_BAT1_CHGEN Li+ BAT/3.7V Battery Box AO3400 4.7uF Figure 7 Li-battery Charging Circuit When the MCU detects that an AC power or an external power adapter is connected, its IO_BAT1_CHGEN port will output a high level to enable the Li-battery power management IC, APL3202, which will charge one 18650 Li-battery. - Page 10 ROW41 ROW42 ROW43 VDD1 VDD1 R142 R144 0.1uF RDB2 CSB2 R143 R145 VDD1 R152 SYNC CSB2 Figure 8 RGB LED Display Circuit (HT1635A/B Section) COM1-1 COM1-5 R111 COM2-1 R123 COM2-5 COM1 COM5 COM9 R109 COM13 R121 AO3400 AO3400 AO3400 AO3400...
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Page 11: Touch Key Detection Circuit
AO3400 Figure 10 Single RGB LED Driving Method Each HT1635A or HT1635B device on the LED display board drives a 8×14 pattern RGB LEDs (8 commons and 42 rows). Two devices combine to drive a 8×28 pattern RGB LED matrix. This demo uses Everlight’s 19-237B RGB SMD LED, which has four pins and is a common cathode type. - Page 12 DATA Figure 12 MCU Control Circuit As the host MCU, the HT66F50 is mainly used to transfer data with the HT1635A/B via a 4-wire interface or an I C interface and control the driver device to drive the RGB LED Matrix for various display functions.
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Page 13: Main Program Flowchart
HT1635A/B Wearable Sports Bracelet LED Display Application S/W Flowchart The HT1635A/HT1635B demo board programs, written using assembly language, include the main program, display subroutine, key scanning subroutine, power supply detection subroutine, Li-battery power detection subroutine and timer interrupt subroutine, etc. Owing to the different communication interfaces, there are two versions of programs that have different data transfer methods but share the remaining subroutines. - Page 14 HT1635A/HT1635B for initial setup. In the main program loop, the host MCU firstly detects the power supply method and then executes a key scanning, system clock update and display update.
- Page 15 Figure 15 HT1635B Initialisation Flowchart (I C Interface) Before the HT1635A/HT1635B can drive the LED Matrix, some initialisation setup should first be executed, such as address setup (only for the HT1635B), COM driving type setup, blinking frequency setup, PWM duty setup, operating mode setup, system setup and LED setup, etc.
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Page 16: Display Subroutine Flowchart
System On Mode? Full screen white light on and blinks three times at a frequency of 0.5Hz After once scroll of HOLTEK logo and welcome characters, enter the Welcome Mode? automatic demonstration screen. If the key is long-pressed, enter the normal display mode. -
Page 17: Touch Key Processing Subroutine Flowchart
HT1635A/B Wearable Sports Bracelet LED Display Application Touch Key Processing Subroutine Flowchart Start Switch to normal display mode. Under this First long-press? mode, short-press key to switch between sub-modes. Switch to fuel consumption display mode. Second Under this mode, short-press key to switch long-press? between sub-modes. -
Page 18: Power Supply Detection Subroutine Flowchart
HT1635A/B Wearable Sports Bracelet LED Display Application Power Supply Detection Subroutine Flowchart Start Turn off DC-DC AC power connected? First power-on? Boost function Power adapter connected? Enable Li-battery charging Li-battery power supply, Set the related flag high Return Figure 18 Power Supply Detection Subroutine Flowchart The MCU uses the IO_ACIN and IO_USBIN ports to detect an AC power connection or an external 5V DC power adapter connection respectively. -
Page 19: Example Code
;LVR Function: Enable ;LVR Voltage Selection: 2.10V ;=============================================================; Conclusions This application note has introduced the HT1635A/HT1635B main features and used some example code and application circuits to show how to use the HT1635A/HT1635B LED driving functions. Attachments • Source Code Files −...
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