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8XC196Kx,8XC196Jx,87C196CA microcontroller family user's manual.1995.pdf
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8XC196Kx, Jx, CA USER’S MANUAL

AD_RESULT (Read)

Address:

1FAAH

 

Reset State:

7F80H

The A/D result (AD_RESULT) register consists of two bytes. The high byte contains the eight mostsignificant bits from the A/D converter. The low byte contains the two least-significant bits from a tenbit A/D conversion, indicates the A/D channel number that was used for the conversion, and indicates whether a conversion is currently in progress.

15

ADRLT9

ADRLT8

ADRLT7

ADRLT6

7

 

 

 

 

 

 

 

ADRLT1

ADRLT0

 

 

 

 

8

ADRLT5

ADRLT4

ADRLT3

ADRLT2

 

 

 

 

0

STATUS

ACH2

ACH1

ACH0

 

 

 

 

Bit

Bit

Function

Number

Mnemonic

 

 

 

 

15:6

ADRLT9:0

A/D Result

 

 

These bits contain the A/D conversion result.

 

 

 

5:4

Reserved. These bits are undefined.

 

 

 

3

STATUS

A/D Status

 

 

Indicates the status of the A/D converter. Up to 8 state times are required

 

 

to set this bit following a start command. When testing this bit, wait at

 

 

least the 8 state times.

 

 

1 = A/D conversion is in progress

 

 

0 = A/D is idle

 

 

 

2:0

ACH2:0

A/D Channel Number

 

 

These bits indicate the A/D channel number that was used for the

 

 

conversion. The 87C196CA, 8XC196Jx devices have six channel inputs.

 

 

These channels are numbered 2–7. The 8XC196Kx devices have eight

 

 

channels, numbered 0–7.

 

 

 

Figure 11-6. A/D Result (AD_RESULT) Register — Read Format

11.6 DESIGN CONSIDERATIONS

This section describes considerations for the external interface circuitry and describes the errors that can occur in any A/D converter. The datasheet lists the absolute error specification, which includes all deviations between the actual conversion process and an ideal converter. However, because the various components of error are important in many applications, the datasheet also lists the specific error components. This section describes those components. For additional information and design techniques, consult AP-406, MCS® 96 Analog Acquisition Primer (order number 270365). Application note AP-406 is also included in Automotive Products and Embedded Microcontrollers handbooks.

11-10

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