si4021 Silicon Laboratories, si4021 Datasheet - Page 19

• Manufacturer Part Number: si4021
• Description: Si4021 Universal Ism Band Fsk Transmitter
• Manufacturer: Silicon Laboratories

9. Wake-Up Timer Command
The wake-up time period can be calculated as:
where M is defined by the <m7 : m0> digital value and R is defined by the <r4 : r0> digital value.
The value of R should be in the range of 0 and 23. The maximum achievable wake-up time period can be up to 24 days.
Note:
Software reset: Sending FE00h command to the chip triggers software reset. For more details see the Reset modes section.
10. Data Transmit Command
In EEPROM operation mode:
In microcontroller slave mode:
This command indicates that the following bitstream coming in via the serial interface is to be transmitted. In EEPROM mode, the 8-bit value
N of bits <n7 : n0> contains the number of data bytes to follow.
Note:
bit
bit
bit
•
•
•
•
•
•
15
15
1
1
7
1
F
This command is not needed if the transmitters’ power management bits (ex, es, ea) are fully controlled by the microcontroller and
TX data comes through the FSK pin.
If the crystal oscillator was formerly switched off (ex=0), the internal oscillator needs t
depends on the type of quartz crystal used.
If the synthesizer was formerly switched off (es=0), the internal PLL needs t
the internal locking process is finished.
In EEPROM mode, before issuing the Data Transmit Command, the power amplifier must be enabled, with the ea or a0 bit in the
Power Management Command.
In EEPROM mode, when N bytes have been read and transmitted the controller continues reading the EEPROM and processing the
data as control commands. This process stops after Sleep Command has been read from the EEPROM.
or continual operation the et bit should be cleared and set at the end of every cycle.
T
wake-up
14
14
1
1
6
1
= M * 2
13
13
1
0
5
0
R
12
12
r4
0
4
0
[ms] ,
11
11
r3
0
3
0
10
10
r2
1
2
1
r1
9
9
1
1
1
r0
8
8
0
0
0
m7
n7
7
7
m6
n6
6
6
m5
n5
5
5
m4
n4
4
4
sp
m3
n3
3
3
startup time. Valid data can be transmitted only when
m2
n2
2
2
m1
n1
1
1
sx
time, to switch on. The actual value
m0
n0
0
0
E000h
POR
POR
- -
IA4221
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