Using the HT66FB5x0 for 2D Joystick Applications C ...Using the HT66FB5x0 for 2D Joystick Application (C Language) 2 Supports 3.3V LDO and internal UDP 1.5k pull-up resistor Internal

Using the HT66FB5x0 for 2D Joystick Application (C Language)

1

Using the HT66FB5x0 for 2D Joystick Applications C Language Example

D/N : AN0323E

Introduction The HT66FB5x0 series of devices are 8-bit A/D type Flash MCUs with a USB interface.

This application note provides a reference for users about how to use the HT66FB550 to

implement a USB 2D Joystick application using C language.

Operating Principle

Joystick Introduction

A joystick is a game controller which works together with game machines and software to

provide players with better playing experience. In this application, the 2D Joystick

includes four operating keys and a Coolie Hat setup by X/Y axis parameters. It is a simple

type joystick using USB communication.

A joystick usually uses two potentiometers, whose resistance change will be converted to

a positional change using the MCU A/D converter. The MCU is configured as a Joystick

USB device by the descriptor settings. When the MCU is connected to a PC, the PC will

automatically install the system-provided Joystick HID driver. Then the PC can identify the

position and key information sent from the MCU through the USB.

The HT66FB550 device includes an integrated A/D, USB SIE, etc., and is suitable for

USB Joystick and other device developments. The following text will introduce how to use

the HT66FB550 to develop a 2D Joystick application with one Coolie Hat and four keys.

HT66FB550 main features:

Flash Program Memory: 8K16

RAM Data Memory: 7688

USB 2.0 Full Speed compatible

Supports 6 endpoints

All endpoints except endpoint 0 can support interrupt and bulk transfer

All endpoints except endpoint 0 can be configured as 8, 16, 32, 64 bytes FIFO size

Endpoint 0 supports control transfer, 8 bytes FIFO


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Supports 3.3V LDO and internal UDP 1.5k pull-up resistor

Internal 12MHz HIRC with 0.25% accuracy for all USB modes

Two 10-bit CTMs, one 10-bit STM and one 16-bit STM

Serial Interface Modules with Dual SPI and I2C interfaces

Supports In System Programming function - ISP

16 channels 12-bit resolution A/D converter

Dual Comparator functions

HT66FB550 A/D Converter Introduction

A/D Converter Registers

ADRL, ADRH: store the converted data, the data format is controlled by ADRFS bit;

ADCR0: controls the A/D power on/off, start function and A/D channel selection;

ADCR1: selects A/D reference voltage and A/D clock source;

ACER0: determines which pins on PB0~PB6 and PA7 are used as A/D converter inputs;

ACER1: determines which pins on PC0~PC7 are used as A/D converter inputs;

A/D Conversion Steps

1) Select the required A/D conversion clock by correctly programming the

ADCK2~ADCK1 bits in the ADCR1 register.

2) Enable the A/D by clearing the ADOFF bit in the ADCR0 register to zero.

3) Select which channel is to be connected to the internal A/D converter by correctly

programming the ACS4~ACS0 bits which are also contained in the ADCR1 and

ADCR0 registers.

4) Select which pins are to be used as A/D inputs and configure them by correctly

programming the ACE15~ACE0 bits in the ACER1~ACER0 registers.

※ If the A/D interrupt is to be used, the A/D converter interrupt bit, ADE, and the

master interrupt control bit, EMI, must both be set high to do this.

5) Setup the START bit in the ADCR0 register from low to high and then low again to

initialise an A/D conversion process.

6) Check the EOCB bit in the ADCR0 register. The conversion process is completed

when the EOCB bit goes low, then the user can read the ADRH and ADRL registers

to obtain the converted value.

※ If both the A/D interrupt and global interrupt are enabled and the stack is not full,

when an A/D conversion process is completed, an A/D interrupt occurs.


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HT66FB550 USB Interface Introduction

The HT66FB550 has a series of registers associated with USB operation: SYSC,

USB_STAT, UINT, USC, USR, UCC, AWR, STLO, STLI, SIES, MISC, UFOEN, UFIEN,

UFC0, UFC1 and FIFOn (n=0~5).

SYSC: used for USB SIE enable/disable control, etc.

USB_STAT: used to indicate USB BUS noise detection and select UDN and UDP

pull-high register, etc.

UINT: used for endpoint interrupts control.

USC: used to select the USB or PS2 mode, indicate USB status, etc.

USR: used to indicate endpoints accessed detection.

UCC: used to select UDP pull-high resistor, MCU clock source, USB clock control and

endpoint FIFO to be accessed.

AWR: used for USB device address setup and remote wake-up control.

STLO, STLI: used for FIFO OUT and IN stall endpoints indication.

SIES: used for USB communication status indication, etc.

MISC: used for FIFO read and write operations, etc.

UFIEN, UFOEN: used for endpoints input and output FIFO control.

UFC0, UFC1: used for endpoints FIFO size selection.

FIFOn: used to store the endpoint accessing data.

For more register information, refer to the datasheet.


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Application Circuit

PA

0/TC

K1/D

BIO

1

NC

2

UD

N/G

PIO

03

UD

P/G

PIO

14

V33O

5

UB

US

/PE

1/AV

DD

/VD

D6

HV

DD

7

VS

S8

PE

3/XT

19

PE

4/XT

210

/RE

S/D

BC

LK

11

PE

212

PE

513

PD0/T

P3_1/O

SC

114

PD1/T

P2_1/O

SC

215

PD

2/TC

K2

16

PD

317

PD

4/TC

K3

18

PD5/T

P1_1

19

PD6/T

P3_0

20

PD7/T

P2_0

21

NC

22

NC

23

NC

24P

B0/S

DO

/SD

A/A

N0

25P

B1/S

DI/S

CL

/AN

126

PB

2/SC

K/A

N2

27P

B3/S

CS

/AN

328

PB4/T

P0_1/A

N4

29P

B5/P

CK

/AN

530

PB

6/INT

1/AN

631

PB

732

PC

0/AN

833

PC

1/AN

934

PC2/A

N10

35

PC3/A

N11

36PC

4/AN

1237

PC5/A

N13

38PC

6/AN

1439

PC7/A

N15

40P

E0/V

DD

IO/V

RE

F41

PA

7/INT

0/AN

742

PA6/T

CK

0/C1-

43PA

5/TP

1_0/C1+

44PA

4/SCSA

/TP0_0/C

1X45

PA

3/SC

KA

/C0-

46P

A2/S

DIA

/C0+

47P

A1/S

DO

A/C

0X48

U2

HT

66FB550

100K

R29

300

R30

0.1uFC

12

VD

D

VC

C0.1uF

C13

KE

Y0

12

34

56

78

910

1112

ICP

/OC

DS

12

J15

DP

I

F1

Fuse

D9

Yellow

Vin

Vout

GN

D

U1

HT

7833

10uF/25V

C6

1 2 3

J16P

A0

UD

N

VD

D

OC

DS

CK

SH

EL

D6

GN

D5

NC

4D

+3

D-

2V

US

B1

7

US

BB

ead FB

1

33R

1633

R17

47P

C10

47P C11

UD

NU

DP

VU

SB

1 2 3

J10

1 2 3

J14

VU

SB

VD

DIN

VE

XT

1 2

P3

0.1uF

C8

10uF/25V

C7

0.1uF

C9

470R

2

D10Y

ellow

470R

1

VD

D

V33O

KE

Y1

KE

Y2

KE

Y3

PD

4P

B0

PB

1

PB

2

PB

3

1

2

3

4

5

6789 10

2D Joystick

12

34

56

J9Header 3X

2

PA

6

PB

4P

A7

VD

D

ST

ICK

_U/D

ST

ICK

_L/R

ST

ICK

_SW

OC

DS

CK

PA

0

UD

NU

DP

OC

DS

CK

PA

6P

A7

PB

0P

B1

PB

2P

B3

PB

4

PD

4

V33O

VD

D

GN

DV

DD

PO

WE

R

KE

Y

2D Joystick

ICP/O

CD

S

US

B


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Program Description

The resistors and capacitors in the USB cable of the USB interface circuit are mainly

used for impedance matching to reduce interference, improve communication stability

and reduce the possibility of data errors during USB data transmission. The USB host

device power uses a bead to provide a noise free power source for the system.

This Joystick is essentially composed of two potentiometers and a switch. The 2D

Joystick circuit mainly uses the A/D converter to convert the joystick position information

to electrical signals. PB4 and PA7 correspond to A/D channel AN4 and AN7, they are

used to sample the Y and X axis displacements respectively. PA6 is used to sample the

switch information. When detecting another four keys, KEY0~KEY3, PD4 first outputs a

low level, PB0~PB3 are setup as inputs and their internal pull-high resistors are enabled.

If a low level is detected on PB0~PB3, which means that one of the four keys has been

pressed, the corresponding key value will be sent to the PC.

USB 2D Joystick Descriptors Introduction

The 2D Joystick is a USB HID device. This section introduces the USB 2D Joystick

descriptors used in this application program.

Device Descriptor

Field Position Size/Byte Name Example

bLength 0 1 Descriptor Length 0x12 bDescriptorType 1 1 Descriptor Type 0x01 bcdUSB 2 2 Protocol Version 0x0110 bDeviceClass 4 1 Device Class 0x00 bDeviceSubClass 5 1 Device Sub-Class 0x00 bDeviceProtocol 6 1 Device Protocol 0x00 bMaxPacketSize0 7 1 Max Packet Size 0x08 idVender 8 2 Vender ID code 0x04d9 idProduct 10 2 Product ID code 0xffff bcdDevice 12 2 Device Version 0x0001 iManufacturer 14 1 Manufacturer Name Index 0x01 iProduct 15 1 Product Name Index 0x02

iSerialNumber 16 1 Product Serial Number

Index 0x00

bNumConfigurations 17 1 Configuration Numbers 0x01

Configuration Descriptor

Field Position Size/Byte Name Example bLength 0 1 Descriptor Length 0x09 bDescriptorType 1 1 Descriptor Type 0x02 bTotalLength 2 2 Configuration Total Length 0x0022 bNumInterfaces 4 1 Interface Numbers 0x01 bConfigurationValue 5 1 Configuration Value 0x01 iConfiguration 6 1 Configuration Name Index 0x00 bmAttributes 7 1 Configuration Attributes 0x80 bMaxPower 8 1 Max Power Consumption 0x32


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bmAttributes:

D7 D6 D5 D4 D3 D2 D1 D0

1 Self-provided

Power RemoteWake-up

0 0 0 0 0

In this application, the power is supplied by the bus, a remote wake-up function is not

supported.

bMaxPower: 2mA as a unit, the maximum power consumption of this application device is

50×2=100mA.

Interface Descriptor

Field Position Size/Byte Name Example bLength 0 1 Descriptor Length 0x09 bDescriptorType 1 1 Descriptor Type 0x04 bInterfaceNumber 2 1 Interface Serial Number 0x00 bAlternateSetting 3 1 Alternate Setting 0x00 bNumEndpoints 4 1 Endpoint Numbers 0x01 bInterfaceClass 5 1 Interface Class 0x03 bInterfaceSubClass 6 1 Interface Sub-Class 0x00 bInterfaceProtocol 7 1 Interface Protocol 0x00 iInterface 8 1 Interface Name Index 0x00

In this application, the interface class is HID (0x03), the interface sub-class and interface

protocol code are both 0x00.

HID Descriptor

Field Position Size/Byte Name Example bLength 0 1 Descriptor Length 0x09 bDescriptorType 1 1 Descriptor Type 0x21 bcdHID 2 2 HID Protocol 0x0110 bCountryCode 4 1 Country Code 0x00

bNumDescriptors 5 1 Subsequent Descriptor

Numbers 0x01

bDescriptorType 6 1 Subsequent Descriptor Type 0x22 wEntityLength 7 2 Subsequent Descriptor Length 0x0052

The subsequent descriptor is a report descriptor, its type code is 0x22.

Endpoint Descriptor

Field Position Size/Byte Name Example bLength 0 1 Descriptor Length 0x07 bDescriptorType 1 1 Descriptor Type 0x05 bEndpointAddress 2 1 Endpoint Address 0x81 bmAttributes 3 1 Endpoint Attributes 0x03 wMaxPacketSize 4 2 Max Packet Size 0x0008 bInterval 6 1 Polling Interval 0x08

bEndpointAddress: 0x81 indicates that endpoint 1 is setup as input.


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D7 D6 D5 D4 D3 D2 D1 D0

In/Out Direction 0 0 0 Endpoint Address

bmAttributes: 0x03 indicates that endpoint transfer type is interrupt transfer.

0x00 0x01 0x02 0x03

Control Transfer Real-time Transfer Bulk Transfer Interrupt Transfer

bInterval: the USB host polling interval, it means how often the host will ask the device for

data. In this application, the polling interval is 8ms.

Report Descriptor 0x05,0x01, //Usage Page (Generic Desktop Control) 0x09,0x04, //Usage (Joystick) 0xa1,0x01, //Collection (Application) 0xa1,0x02, //Collection (Logical) 0x75,0x08, //Report Size (8) 0x95,0x04, //Report Count (4) 0x15,0x00, //Logical Minimum (0) 0x26,0xff,0x00, //Logical_Maximum (255) 0x35,0x00, //Physical Minimum (0) 0x46,0xff,0x00, //Physical Maximum (255) 0x09,0x30, //Usage (X) 0x09,0x31, //Usage (Y) 0x09,0x02, //Usage (Reserved) 0x09,0x02, //Usage (Reserved) 0x81,0x02, //Input(Data,Var,Abs) 0x75,0x01, //Report Size (1) 0x95,0x05, //Report Count (5) 0x25,0x01, //Logical Maximum (1) 0x45,0x01, //Physical Maximum (1) 0x05,0x09, //Usage Page (Button) 0x19,0x01, //Usage Minimum (1) 0x29,0x05, //Usage Maximum (5) 0x81,0x02, //Input (Data, Variable, Absolute) 0x06,0x00,0xff, //Usage Page (Reserved) 0x75,0x01, //Report Size (1) 0x95,0x1b, //Report Count (27) 0x25,0x01, //Logical Maximum (1) 0x45,0x01, //Physical Maximum (1) 0x09,0x01, //Usage (Reserved) 0x81,0x02, //Input (Data, Variable, Absolute) 0xc0, //End Collection 0xa1,0x02, //Collection (Logical) 0x75,0x08, //Report Size (8) 0x95,0x07, //Report Count (7) 0x46,0xff,0x00, //Physical Maximum (255) 0x26,0xff,0x00, //Logical Maximum (255) 0x09,0x02, //Usage (Reserved) 0x91,0x02, //Feature (Data, Variable) 0xc0, //End Collection 0xc0 //End Collection


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Byte D7 D6 D5 D4 D3 D2 D1 D0

0 X displacement

1 Y displacement 2 Reserved 3 Reserved 4 Reserved Switch Key3 Key2 Key1 Key05 Reserved 6 Reserved 7 Reserved

S/W Flowchart

This application program is mainly to enumerate the device as a 2D Joystick, then use the

A/D converter to sample the X/Y displacement and the pressed status of five keys. When

the PC is accessing endpoint 1, the associated data will be sent out.

The program contains several parts, main program, USB interrupt subroutine, endpoint

FIFO accessing subroutine, endpoint 1 and 0 data processing subroutine, Coolie Hat X/Y

displacement sampling and key scanning subroutine.

Main Program Flowchart

Start

Initialise I/O ports, A/D, timer and USB

Enable USB interrupt and global

interrupt EMI

suspend？Enter halt,

wait for wake-up

enumerationfinished?

Joystick and key scanning,

update data buffer

Y

Y

N

N


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USB Interrupt Subroutine Flowchart


10

Coolie Hat X/Y Displacement Sampling and Key Scanning

Subroutine

This subroutine is mainly used to implement four keys and Joystick switch scanning and

status updating. It uses AN4 and AN7 to sample Y and X displacements respectively.


11

Endpoint 0 Data Processing Subroutine Flowchart

Endpoint 0 data processing subroutine implements the following functions:

1. Analyse the setup token to determine the descriptor type and data length.

2. Analyse the in token and transmit data according to the data length.


12

Endpoint 1 Data Processing Subroutine Flowchart

Start

Clear endpoint 1 accessed flag

Clear key scanning finished flag; clear

transmit data buffer

Store X and Y axis data to buffer0 and buffer1

Key status changed?

Y

N

tx=1, transmit buffer data via endpoint 1

End

USB enumeration and key scanning finished?

Y

N

Buffer4=preBTNpreBTN=0

This subroutine uses endpoint 1 to transmit X/Y axis and key buffer data to the host.

Endpoint FIFO Accessing subroutine Flowchart


13

Test Result

Here we use the Windows XP system-provided game controller to test the 2D Joystick

usage effect. Open the “Game Controller” in the control panel, connect the device to the

PC, then the device will be shown in the controller window. Double-click the installed

device to start testing. When the joystick is moved, the “+” sign in the test window should

also move. Press four keys and the Joystick switch and the five button signs in the test

window should turn red.

Program Example Program Language: C Language HOLTEK IDE3000 Compiler： Holtek C Compiler V3.10 Configuration Option： High Freq.OSC: HIRC Low Freq.OSC: LIRC Fsub clock source: LIRC ;other option selected by user.

For other program codes and descriptions refer to the attachment.

Conclusion Using the HT66FB550 as a master MCU, this text has introduced how to use the A/D

converter and USB interface to achieve a simple USB 2D Joystick which contains a

Coolie Hat and four keys.

Attachment

HT66FB550_2DJY.rar

Using the HT66FB5x0 for 2D Joystick Applications C ...Using the HT66FB5x0 for 2D Joystick Application (C Language) 2 Supports 3.3V LDO and internal UDP 1.5k pull-up resistor Internal

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