MC33972 Datasheet, PDF(15/28 Page) Motorola, Inc – Multiple Switch Detection Interface with Suppressed Wake-Up

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

MC33972 Datasheet, PDF (15/28 Pages) Motorola, Inc – Multiple Switch Detection Interface with Suppressed Wake-Up

◁

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

Table 10. Tri-State Command

Tri-State Commands

Command Bits

23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

0 0 0 0 1 0 0 1 X X X X X X X X sp7 sp6 sp5 sp4 sp3 sp2 sp1 sp0

0 0 0 0 1 0 1 0 X X sg13 sg12 sg11 sg10 sg9 sg8 sg7 sg6 sg5 sg4 sg3 sg2 sg1 sg0

ANALOG SELECT REGISTER

The analog voltage on switch inputs may be read by the

MCU using the analog command (Table 11). Internal to the

IC is a 22-to-1 analog multiplexer. The voltage present on the

selected input pin is buffered and made available on the

AMUX output pin. The AMUX output pin is clamped to a

maximum of VDD volts regardless of the higher voltages

present on the input pin. After an input has been selected as

the analog, the corresponding bit in the next SO data stream

will be logic [0]. When selecting a channel to be read as

analog, the user must also set the desired current (16 mA,

2.0 mA, or high impedance). Setting bit 6 and bit 5 to 0,0

selects the input as high impedance. Setting bit 6 and bit 5 to

0,1 selects 2.0 mA, and 1,0 selects 16 mA. Setting bit 6 and

bit 5 to 1,1 in the Analog Select Register is not allowed and

will place the input as an analog input with high impedance.

Analog currents set by the analog command are pullup

currents for all SGn and SPn inputs (Table 11). The analog

command does not allow pulldown currents on the SPn

inputs. Setting the current to 16 mA or 2.0 mA may be useful

for reading sensor inputs. Further information is provided in

the Typical Applications section of this datasheet beginning

on page 20. The MCU may change or update the Analog

Select Register via software at any time in Normal mode.

Table 11. Analog Command

Analog Command

Not used

Current Select Analog Channel Select

23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6

5 43210

0 0 0 0 0 1 1 0 X X X X X X X X X 16 mA 2.0 mA 0 0 0 0 0

Analog Integrated Circuit Device Data

Freescale Semiconductor

33972

▷