EM6821 datasheet(56/68 Pages) EMMICRO

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EM6821

www.emmicroelectronic.com

18. Mask Options

Most options which in many µControllers are realized as metal mask options are directly user selectable with

the option registers, therefore allowing a maximum freedom of choice .See chapter: Option Register Memory

Map.

The following options can be selected at the time of programming the metal mask ROM, except the LCD Segment

allocation which is defined using the interconnect metal2 mask.

18.1 Input / Output Ports

18.1.1 Port A Metal Options

18.1.2 Port A Metal Options

Pull-up or no pull-up can be selected

for each port A input. A pull-up

selection is excluding a pull-down on

the same input.

Pull-down (default) or no pull-down

can be selected for each port A

input.

pull-down

selection

excluding a pull-up on the same

input.

The total pull value (pull-up or pull-

down) is a series resistance out of

the resistance R1 and the switching

transistor. As a switching transistor

the user can choose between a high

impedance

(weak)

low

impedance (strong) switch. Weak,

strong or none must be chosen. The

default is strong. The default resistor

R1 value is 90 KOhm. The user may

choose a different value lower than

90kOhm. However the value must first be checked and agreed by EM Microelectronic Marin SA. Refer also to

chapter 19.2 and 19.1 for the pull values.

To select an option put an X in

column 1,2 and 4 and reconfirm

the R1 value in column 3.

The default value is : Strong pull-

down with R1=90 KOhm

To select an option put an X in

column 1,2 and 4 and reconfirm

the R1 value in column 3.

The default value is : Strong pull-up

with R1=90 KOhm

Figure 38. Port A Pull Options

Resistor R1

MPAPDweak[n]

Weak Pull-down

MPAPDstrong[n]

Strong Pull-down

MPAPUweak[n]

Weak Pull-up

MPAPUstrong[n]

Strong Pull-up

Pull-up Control

PA[n]

Terminal

100 KOhm

No Pull-up

No Pull-down

Pull-down Control

Input Circuitry

Option

Name

Strong

Pull-

down

Pull-

down

Value

Typ.90k

Pull-

down

MPAPD[3]

PA3 input pull-down

MPAPD[2]

PA2 input pull-down

MPAPD[1]

PA1 input pull-down

MPAPD[0]

PA0 input pull-down

Option

Name

Strong

Pull-up

Weak

Pull-up

Value

typ.90k

Pull-up

MPAPU[3]

PA3 input pull-up

MPAPU[2]

PA2 input pull-up

MPAPU[1]

PA1 input pull-up

MPAPU[0]

PA0 input pull-up

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