Zilog Z86193 Manual do Utilizador descarregar pdf (Página 82)

CPU

User Manual

UM001604-0108 Input/Output Ports

•

Low EMI output drivers have resistance of 200 Ω (typical)

•

Low EMI Oscillator

•

All output drivers are approximately 25 percent of the standard drive

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Internal SCLK ÷ TCLK = XTAL operation limited to a maximum of 4 MHz–250 ns

cycle time, when Low EMI Oscillator is selected and system clock (SCLK = XTAL,

SMR Reg. Bit D1 = 1)

For Z8

MCUs having the PCON register feature, the following bits control the Low EMI

options.

Low EMI Port 0—Port 0, D3 can be configured as a Low EMI Port by resetting this bit

(D3 = 0) or configured as a Standard Port by setting this bit (D3 = 1). The default value

is 1.

Low EMI Port 1—Port 1, D4 can be configured as a Low EMI Port by resetting this bit

(D4 = 0) or configured as a Standard Port by setting this bit (D4 = 1). The default value

is 1.

Low EMI Port 2—Port 2, D5 can be configured as a Low EMI Port by resetting this bit

(D5 = 0) or configured as a Standard Port by setting this bit (D5 = 1). The default value

is 1.

Low EMI Port 3—Port 3, D6 can be configured as a Low EMI Port by resetting this bit

(D6 = 0) or configured as a Standard Port by setting this bit (D6 = 1). The default value

is 1.

Low EMI OSC—This D7 bit of the PCON Register controls the Low EMI oscillator. A 1

in this location configures the oscillator with standard drive, while a 0 configures the

oscillator with low noise drive. The Low-EMI mode reduces the drive of the oscillator

(OSC). The default value is 1. XTAL ÷ 2 mode is not affected by this bit.

The maximum external clock frequency is 4 MHz when running in the Low EMI oscillator

mode.

Refer to the selected device product specification for availability of the Low EMI feature

and programming options.

Input Protection

All CMOS ROM Z8 MCUs have I/O pins with diode input protection. There is a diode

from the I/O pad to V

and to V

. See Figure 63 on page 76.

Note:

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