Intel 8XC196NT 87C196CB SUPPLEMENT, 1. A/D Command ADCOMMAND Register, Adcommand, Function, M1 M0

Models: 8XC196NT 87C196CB

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AD_COMMAND

87C196CB SUPPLEMENT

AD_COMMAND

Address:

1FACH

 

Reset State:

C0H

The A/D command (AD_COMMAND) register selects the A/D channel number to be converted, controls whether the A/D converter starts immediately or with an EPA command, and selects the conversion mode.

7

M1

M0

 

 

 

 

0

GO

ACH2

ACH1

ACH0

 

 

 

 

Bit

Bit

 

 

Function

Number

Mnemonic

 

 

 

 

 

 

 

 

7:6

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

 

 

 

 

5:4

M1:0

A/D Mode

 

 

 

These bits determine the A/D mode.

 

 

M1 M0

Mode

 

 

0

0

10-bit conversion

 

 

0

1

8-bit conversion

 

 

1

0

threshold detect high

 

 

1

1

threshold detect low

 

 

 

3

GO

A/D Conversion Trigger††

 

 

Writing this bit arms the A/D converter. The value that you write to it

 

 

determines at what point a conversion is to start.

 

 

0

= EPA initiates conversion

 

 

1

= start immediately

 

 

 

2:0

ACH2:0

A/D Channel Selection

 

 

Write the A/D conversion channel number to these bits. The 87C196CB

 

 

has eight A/D channel inputs, numbered 0–7.

 

 

 

 

 

While a threshold-detection mode is selected for an analog input pin, no other conversion can be started. If another value is loaded into AD_COMMAND, the threshold-detection mode is disabled and the new command is executed.

††It is the act of writing to the GO bit, rather than its value, that starts a conversion. Even if the GO bit has the desired value, you must set it again to start a conversion immediately or clear it again to arm it for an EPA-initiated conversion.

Figure 6-1. A/D Command (AD_COMMAND) Register

6-2

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Intel 8XC196NT user manual 87C196CB SUPPLEMENT, 1. A/D Command ADCOMMAND Register, Adcommand, Function, Number, M1 M0, Mode