8XC196MC, MD, MH USER’S MANUAL

CCR1 (Continued)

no direct access

The chip configuration 1 (CCR1) register enables the watchdog timer and selects the bus timing mode. Two of its bits combine with three bits of CCR0 to control wait states and bus width.

7

1

1

0

1

 

 

 

 

0

WDE

BW1

IRC2

0

 

 

 

 

Bit

Bit

 

 

 

Function

Number

Mnemonic

 

 

 

 

 

 

 

 

 

 

 

1

IRC2

Ready Control

 

 

 

This bit, along with IRC0 (CCR0.4), IRC1 (CCR0.5), and the READY pin

 

 

determine the number of wait states that can be inserted into the bus

 

 

cycle. While READY is held low, wait states are inserted into the bus

 

 

cycle until the programmed number of wait states is reached. If READY is

 

 

pulled high before the programmed number of wait states is reached, no

 

 

additional wait states will be inserted into the bus cycle.

 

 

IRC2

IRC1

IRC0

 

 

 

0

0

0

zero wait states

 

 

0

X

1

illegal

 

 

1

1

X

illegal

 

 

1

0

0

one wait state

 

 

1

0

1

two wait states

 

 

1

1

0

three wait states

 

 

1

1

1

infinite

 

 

If you choose the infinite wait states option, you must keep P5.6

 

 

configured as the READY signal. Also, be sure to add external hardware

 

 

to count wait states and pull READY high within a specified time.

 

 

Otherwise, a defective external device could tie up the address/data bus

 

 

indefinitely.

 

 

 

 

 

0

0

Reserved; for compatibility with future devices, write zero to this bit.

 

 

 

 

 

 

The CCRs are loaded with the contents of the chip configuration bytes (CCBs) after reset, unless the microcontroller is entering programming modes (see “Entering Programming Modes” on page 16-13), in which case the programming chip configuration bytes (PCCBs) are used. The CCBs reside in nonvolatile memory at addresses 2018H (CCB0) and 201AH (CCB1).

Figure 15-2. Chip Configuration 1 (CCR1) Register

15.3 BUS WIDTH AND MULTIPLEXING

The external bus can operate as either a 16-bit multiplexed address/data bus or as a multiplexed 16-bit address/8-bit data bus (Figure 15-3).

15-10

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Intel 8XC196MH, 8XC196MD, 8XC196MC manual BUS Width and Multiplexing, CCR1