
M
Low-Cost, Crystal-Based, Programmable,
ASK/FSK Transceiver with Fractional-N PLL
______________________________________________________________________________________
21
Continuous Receive Mode (DRX = 0)
In continuous receive mode, individual analog modules
can be powered on directly through the power configu-
ration register (register 0x00). The SLEEP bit (bit 0 in
register 0x01) overrides the power configuration regis-
ters and puts the device into deep-sleep mode when
set. It is also necessary to write the frequency divisor of
the external crystal in the oscillator frequency register
(register 0x05) to optimize image rejection and to
enable accurate calibration sequences for the polling
timer and the FSK demodulator. This number is the
integer result of f
XTAL
/ 100kHz.
If the FSK receive function is selected, it is necessary to
perform an FSK calibration to allow operation; other-
wise, the demodulator is saturated. Polling timer cali-
bration is not necessary. See the
Calibration section
for
more information.
Discontinuous Receive Mode (DRX = 1)
In the discontinuous receive mode (DRX = 1), the
receiver modules set to logic 1 by the power register
(0x00) of the MAX7032 toggle between OFF and ON,
according to internal timers t
OFF
, t
CPU
, t
RF
, and t
ON
. It
is also necessary to write the frequency divisor of the
external crystal in the oscillator frequency register (reg-
ister 0x05). This number is the integer result of f
XTAL
/
100kHz. Before entering the discontinuous receive
mode for the first time, it is also necessary to calibrate
the timers (see the
Calibration section
).
The MAX7032 uses a series of internal timers (t
OFF
,
t
CPU
, t
RF
, and t
ON
) to control its power-up sequence.
The timer sequence begins when both
CS
and DIO are
one. The MAX7032 has an internal pullup on the DIO
pin, so the user must tri-state the DIO line when
CS
goes high.
The external CPU can then go to a sleep mode during
t
OFF
. A high-to-low transition on DIO, or a low level on
DIO serves as the wake-up signal for the CPU, which
must then start its wake-up procedure, and drive DIO
low before t
LOW
expires (t
CPU
+ t
RF
+ t
ON
). Once t
RF
expires and t
ON
is active, the MAX7032 enables the
data output. The CPU must then keep DIO low for as
long as it may need to analyze any received data.
Releasing DIO after t
ON
expires causes the MAX7032
to pull up DIO, reinitiating the t
OFF
timer.
DATA
NAME (ADDRESS)
D7
D6
D5
D4
D3
D2
D1
D0
POWER[7:0] (0x00)
CONTRL[7:0] (0x01)
CONF0[7:0] (0x02)
CONF1[7:0] (0x03)
OSC[7:0] (0x05)
t
OFF
[15:8] (0x06)
t
OFF
[7:0] (0x07)
t
CPU
[7:0] (0x08)
t
RF
[15:8] (0x09)
t
RF
[7:0] (0x0A)
t
ON
[15:8] (0x0B)
t
ON
[7:0] (0x0C)
TxLOW[15:8] (0x0D)
TxLOW[7:0] (0x0E)
TxHIGH[15:8] (0x0F)
TxHIGH[7:0] (0x10)
STATUS[7:0] (0x1A)
LNA
AGCLK
Mode
AGC
GAIN
T/
R
ACAL
OSC6
t
OFF
14
t
OFF
6
t
CPU
6
t
RF
14
t
RF
6
t
ON
14
t
ON
6
TxL14
TxL6
TxH14
TxH6
GAINS
MIXER
TRK_EN
MGAIN
CLKOF
OSC5
t
OFF
13
t
OFF
5
t
CPU
5
t
RF
13
t
RF
5
t
ON
13
t
ON
5
TxL13
TxL5
TxH13
TxH5
CLKON
BaseB
PkDet
PCAL
OFPS1
CDIV0
OSC3
t
OFF
11
t
OFF
3
t
CPU
3
t
RF
11
t
RF
3
t
ON
11
t
ON
3
TxL11
TxL3
TxH11
TxH3
0
PA
FCAL
OFPS0
DT2
OSC2
t
OFF
10
t
OFF
2
t
CPU
2
t
RF
10
t
RF
2
t
ON
10
t
ON
2
TxL10
TxL2
TxH10
TxH2
0
RSSIO
CKOUT
ONPS1
DT1
OSC1
t
OFF
9
t
OFF
1
t
CPU
1
t
RF
9
t
RF
1
t
ON
9
t
ON
1
TxL9
TxL1
TxH9
TxH1
PCALD
X
SLEEP
ONPS0
DT0
OSC0
t
OFF
8
t
OFF
0
t
CPU
0
t
RF
8
t
RF
0
t
ON
8
t
ON
0
TxL8
TxL0
TxH8
TxH0
FCALD
—
DRX
CDIV1
OSC4
t
OFF
12
t
OFF
4
t
CPU
4
t
RF
12
t
RF
4
t
ON
12
t
ON
4
TxL12
TxL4
TxH12
TxH4
0
—
OSC7
t
OFF
15
t
OFF
7
t
CPU
7
t
RF
15
t
RF
7
t
ON
15
t
ON
7
TxL15
TxL7
TxH15
TxH7
LCKD
Table 4. Register Configuration