MINIMUM HARDWARE CONSIDERATIONS

The 8XC196MH provides the option of an internal-only reset or an internal reset that is also re- flected externally (by the RESET# pin). The GEN_CON register controls whether an internal re- set asserts the external RESET# signal and indicates the source of the most recent reset. Figure 13-8 describes the general configuration register, GEN_CON.

GEN_CON

Address:

1FA0H

(8XC196MH)

Reset State:

00H

The GEN_CON register controls whether an internal reset asserts the external RESET# signal and indicates the source of the most recent reset.

8XC196MH

7

RSTS

 

 

 

 

0

DR0

 

 

 

 

Bit

Bit

 

 

Function

Number

Mnemonic

 

 

 

 

 

 

 

 

7

RSTS

Reset source (read-only status bit)

 

 

0

=

external reset (RESET# pin asserted)

 

 

1

=

internal reset (watchdog overflow, illegal IDLPD key, or RST

 

 

 

 

instruction)

 

 

 

6:1

Reserved; for compatibility with future devices, write zeros to these bits.

 

 

 

0

DRO

Disable RESET# out

 

 

0

=

an internal reset asserts the RESET# pin.

 

 

1

= an internal reset has no effect on the RESET# pin; the RESET# pin is

 

 

 

 

pulled high (inactive).

 

 

 

 

 

Figure 13-8. General Configuration Register (GEN_CON)

The following events will reset the device (see Figure 13-9):

an external device pulls the RESET# pin low

the CPU issues the reset (RST) instruction

the CPU issues an idle/powerdown (IDLPD) instruction with an illegal key operand

the watchdog timer (WDT) overflows

The following paragraphs describe each of these reset methods in more detail.

13-9

Page 294
Image 294
Intel 8XC196MD, 8XC196MH, 8XC196MC manual Gencon, Rsts DR0, Dro