Si4021

16

6. Low Battery Detector Command

bit

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

POR

1

1

0

0

0

0

1

0

dwc

0

ebs

t4

t3

t2

t1

t0

C200h

Bit 7 <dwc> Disables the Wake-up timer periodical (every 30 second) calibration if this bit is set.

Bit 5 <ebs> Enables the TX bit synchronization circuit. The data rate must be set by the Data Rate Command.

TX bit2

TX bitN

TX bit1

TX Data

(RF modulator input)

SPI commands

(nSEL, SCK, SDI)

FSK or SDI

nIRQ

Power Man

ea=1

Bit time

ea=0

Power Man

LBD&Bsync

ebs=1

nIRQ

Data Rate

Set the DR

1.6us

TX bitN-1

TX bitN

TX bit1

//

//

//

//

//

//

nIRQ

The 5-bit value T of <t4 : t0> determines the threshold voltage V

V

7. Sleep Command

bit

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

POR

1

1

0

0

0

1

0

0

s7

s6

s5

s4

s3

s2

s1

s0

C410h

The effect of this command depends on the Power Management Command. It immediately disables the power amplifier (if a0=1 and ea=0)

and the synthesizer (if a1=1 and es=0). Stops the crystal oscillator after S periods of the microcontroller clock (if a1=1 and ex=0) to enable

the microcontroller to execute all necessary commands before entering sleep mode itself. The 8-bit value S is determined by bits <s7 : s0>.