Register Descriptions

Field

Reset

R/W:

Field

Reset

R/W: Address

15

14

13

12

11

 

 

 

 

8

MUX

 

 

 

TRG

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0000_0000

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R/W

 

R

 

 

R/W

 

 

 

 

R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

6

5

4

3

 

2

1

0

QPR6

 

QPR5

 

 

QPR4

 

QPR3

 

QPR2

 

QPR1

QPR0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0001_0011

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R

 

 

 

 

 

 

 

R/W

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IPSBAR + 0x19_000a, 0x19_000b

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 27-8. QADC Control Register 0 (QACR0)

Table 27-4. QACR0 Field Descriptions

Bit(s)

Name

Description

 

 

 

 

 

15

MUX

Externally multiplexed mode. Configures the QADC for operation in externally multiplexed

 

 

mode, which affects the interpretation of the channel numbers and forces the MA[1:0] signals

 

 

to be outputs.

 

 

1 Externally multiplexed, up to 18 possible channels

 

 

0 Internally multiplexed, up to 8 possible channels

 

 

 

 

 

14–13

Reserved, should be cleared.

 

 

 

 

 

12

TRG

Trigger assignment. Determines the queue assignment of the ETRIG[2:1] signals.

 

 

1 ETRIG1 triggers queue 2; ETRIG2 triggers queue 1.

 

 

0 ETRIG1 triggers queue 1; ETRIG2 triggers queue 2.

 

 

 

 

 

11–7

Reserved, should be cleared.

 

 

 

 

 

6–0

QPR

Prescaler clock divider. Selects the system clock divisor to generate the QADC clock as

 

 

Table 27-5shows. The resulting QADC clock rate can be given as:

 

 

fQCLK =

fSYS

 

 

 

 

 

 

2(QPR[6:0] + 1)

 

 

where:

 

 

1 ≤ QPR[6:0] ≤ 127.

 

 

If QPR[6:0] = 0, then the QPR register field value is read as a 1 and the prescaler divisor is 2.

 

 

The prescaler should be selected so that the QADC clock rate is within the required fQCLK

 

 

range. See MCF5282 Electrical Characteristics.

 

 

 

 

 

27-12

MCF5282 User’s Manual

MOTOROLA

Page 596
Image 596
Motorola MCF5282, MCF5281 user manual Qadc Control Register 0 QACR0 QACR0 Field Descriptions, QPR6