Register Descriptions

the current CCW. The bits in this register are read anytime (except during stop mode), write anytime (except during stop mode).

 

15

10

9

8

Field

 

P

 

BYP

 

 

 

 

 

 

Reset

0000_00

 

 

Unaffected

 

 

 

 

 

R/W:

R

 

 

R/W

 

 

 

 

 

 

Field

Reset

R/W: Address

7

6

5

4

3

2

1

0

IST1

IST0

CHAN5

CHAN4

CHAN3

CHAN2

CHAN1

CHAN0

 

 

 

 

 

 

 

 

Undefined

R

IPSBAR + 0x19_0200, 0x19_027e

Figure 27-14. Conversion Command Word Table (CCW)

Table 27-14. CCW Field Descriptions

Bit(s)

Name

 

Description

 

 

 

15–10

Reserved, should be cleared.

 

 

 

9

P

Pause. Allows subqueues to be created within queue 1 and queue 2. The QADC performs the

 

 

conversion specified by the CCW with the pause bit set and then the queue enters the pause

 

 

state. Another trigger event causes execution to continue from the pause to the next CCW.

 

 

1

Enter pause state after execution of current CCW.

 

 

0

Do not enter pause state after execution of current CCW.

 

 

NOTE: The P bit does not cause the queue to pause in software-initiated modes or externally

 

 

gated modes.

 

 

 

8

BYP

Sample amplifier bypass. Enables the amplifier bypass mode for a conversion and subsequently

 

 

changes the timing. The initial sample time is eliminated, reducing the potential conversion

 

 

time by two QCLKs. However, due to internal RC effects, a minimum final sample time of four

 

 

QCLKs must be allowed. When using this mode, the external circuit should be of low source

 

 

impedance. Loading effects of the external circuitry need to be considered because the benefits

 

 

of the sample amplifier are not present.

 

 

1

Amplifier bypass mode enabled

 

 

0

Amplifier bypass mode disabled

 

 

NOTE: BYP is maintained for software compatibility but has no functional benefit on this

 

 

version of the QADC.

 

 

 

 

MOTOROLA

Chapter 27. Queued Analog-to-Digital Converter (QADC)

27-27

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Image 611
Motorola MCF5281, MCF5282 user manual Byp, IST1 IST0