TSS400-S1

µPOWER PROGRAMMABLE HIGH-PRECISION

SENSOR SIGNAL PROCESSOR

SLMS001 – D4071, JANUARY 1993

POST OFFICE BOX 655303

7

analog-to-digital converter (ADC) (see Figure 2)

The TSS400-S1 offers a 12-bit ratiometric successive approximation ADC. Sensors are interfaced to this

converter via the 4-multiplexed ( 4-MUX ) analog inputs ( A1 – A4 ). The analog conversion operation is executed

with the MEASR instruction. The SMPL interpreter automatically switches the internal digit latches DL9, DL10,

and DL11 such that the ADC is connected to the analog input line specified by the MEASR operand. Table 3

lists the instructions required to access all four analog inputs.

Table 3. Instructions Required to Access Analog Inputs

INSTRUCTION

OPERAND

DL9

DL10

DL11

ACTION

MEASR

0

0

1

0

Connect A1 to the ADC

MEASR

1

0

0

0

Connect A2 to the ADC

MEASR

2

0

1

1

Connect A3 to the ADC

MEASR

3

0

0

1

Connect A4 to the ADC

CHKBATT

X

1

X

X

Check current supply voltage against value in FLAC

ADJBATT

X

1

X

X

Set minimum supply voltage point

A / D conversion and switches it off immediately after the conversion is complete. The MEASR instruction is

followed by a BYTE instruction. The operand of the BYTE instruction specifies the number of conversions to

be made and whether the conversions are to be compensated or noncompensated. A noncompensated

measurement is a single A / D conversion. A compensated measurement is defined as a measurement where

two conversions are made, one conversion with the ADC comparator connected normally and the other

conversion with the comparator inputs reversed. The two results are added together so any comparator offsets

cancel. The interpreter automatically takes care of all required switching to perform the specified type of

conversion.

the sensors is independent of the supply voltage.