SAA5288 查看數據表（PDF） - Philips Electronics

零件编号

产品描述 (功能)

比赛名单

SAA5288

TV microcontroller with full screen On Screen Display (OSD)

Philips Electronics 

Philips Semiconductors

TV microcontroller with full screen

On Screen Display (OSD)

Preliminary specification

SAA5288

7.3.7 SOFTWARE ADC

Up to 4 successive approximation ADCs can be

implemented in software by making use of the on-chip 8-bit

DAC and multiplexed voltage comparator. The software

ADC uses 4 analog inputs which are multiplexed with P3.0

to P3.3.

Table 9 ADC input channel selection

CH1

0

0

1

1

CH0

0

1

0

1

INPUT PIN

P3.3/ADC3

P3.0/ADC0

P3.1/ADC1

P3.2/ADC2

The control of the ADC is achieved using the Special

Function Registers SAD and SADB.

SAD.CH1 and SAD.CH0 select one of the four inputs to

pass to the comparator. The other comparator input

comes from the DAC, whose value is set by SAD.SAD7

(MSB) to SAD.SAD4 and SADB.SAD3 to SADB.SAD0

(LSB). The setting of the value SAD.SAD7 to SAD.SAD4

must be performed at least 1 instruction cycle before the

setting of SAD.ST to ensure comparison is made using the

correct SAD.SAD7 to SAD.SAD4 value.

The output of the comparator is SAD.VHI, and is valid after

1 instruction cycle following the setting of SAD.ST to

logic 1.

handbPoo3k.,0halfpage

P3.1

P3.2

MULTIPLEXER

P3.3

ST

C1

1D

VH1

8-BIT DAC

CH1, CH0

REF−

REF+

SAD7 to SAD0

MGL115

Fig.3 SAD block diagram.

1997 Jun 24

11

Share Link: