LPC47M14X datasheet(122/205 Pages) SMSC

122 / 205 page

SMSC DS – LPC47M14X

Page 122

Rev. 03/19/2001

6.18 SECURITY FEATURE

The following register describes the functionality to support security in the LPC47M14x.

6.18.1

GPIO Device Disable Register Control

The GPIO pin GP43 is used for the Device Disable Register Control (DDRC) function. Setting bits[3:2] of the GP43

configuration register to ‘01’, selects the DDRC function for the GP43 pin. When bits[3:2]=01 the GP43 pin is an

input, with non-inverted polarity. Bits[3:2] cannot be cleared by writing to these bits; they are cleared by VTR POR,

VCC POR and Hard Reset. That is, when the DDRC function is selected for this pin, it cannot be changed, except by a

VCC POR, hard reset or VTR POR.

When the DDRC function is selected for GP43, the Device Disable register is controlled by the value of the GP43 pin

as follows:

If the GP43 pin is high, the Device Disable Register is Read-Only.

If the GP43 pin is low, the Device Disable Register is Read/Write.

6.18.2

Device Disable Register

The Device Disable Register is located in the PME register block at offset 0x22 from the PME_BLK base I/O address

in logical device A. Writes to this register are blocked when the GP43 pin is configured for the Device Disable

The configuration register for the device disable register is defined in the “Runtime Registers” section.

6.19 GAME PORT LOGIC

The LPC47M14x implements logic to support a dual game port. This logic includes the following for each game port:

two 555 timers, two game port RC constant inputs (x-axis and y-axis), two game port button inputs and game port

interface logic. The implementation of the Game Port uses a simple A/D converter constructed from a 555 timer to

digitize the analog value of a potentiometer for the x-axis and y-axis of the joystick.

The figure below illustrates the implementation of the game port logic in the LPC47M14x.

Game software will write a byte to the game port to reset it, and then poll (read) the port until the x and y-axis RC time

constant pins (TIMA,B) time out (return to zero). The elapsed time indicates the resistance value of the potentiometer

and in turn, the position of the joystick.

JOYR

Joystick 1 Button 1

Joystick 1 Button 2

556

OUT1A

OUT1B

TRIG1A

TRIG1B

X-Axis

Y-Axis

TIM1A

TIM1B

JOYW

Vcc = 5V

Internal To LPC47M14x

Joystick 1

556

OUT2A

OUT2B

TRIG2A

TRIG2B

X-Axis

Y-Axis

TIM2A

TIM2B

Vcc = 5V

Joystick 2

Joystick 2 Button 1

Joystick 2 Button 2

J1B1

J1B2

J2B1

J2B2

J1X

J1Y

J2X

J2Y

Game Port

Vcc = 5V

Internal To Joysticks

LPC47M14X Datasheet(PDF) 122 Page - SMSC Corporation

LPC47M14X Datasheet(HTML) 122 Page - SMSC Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL