MC33596 Datasheet, PDF (30/58 Pages) Freescale Semiconductor, Inc – PLL Tuned UHF Receiver for Data Transfer Applications

Configuration, Command, and Status Registers
If AFFC is set, AFF[1:0] allow the overall receiver sensitivity to be improved by reducing the average
filter cut-off frequency. The typical preamble duration of three Manchester zeroes or ones at the data rate
must then be increased, as shown in Table 14.
Table 14. Minimum Number of Manchester Symbols in Preamble
versus DR[1:0] and AFF[1:0]
DR[1:0]
00
01
10
11
00
3
6
12
24
01
—
3
6
12
AFF[1:0]
10
—
—
3
6
11
—
—
—
3
16.2 Command Register
Figure 21 describes the Command register, COMMAND.
Bit Name
Reset Value
Bit 7
AFFC
0
Bit 6
IFLA
0
Bit 5
Bit 4
Bit 3
Bit 2
—
RSSIE
EDD
RAGC
0
0
1
0
Figure 21. COMMAND Register
Bit 1
FAGC
0
Bit 0
—
1
Addr
$03
AFFC (Average Filter Frequency Control) enables direct control of the average filter cut-off frequency.
0 = Average filter cut-off frequency is defined by DR[1:0]
1 = Average filter cut-off frequency is defined by AFF[1:0]
IFLA (IF Level Attenuation) controls the maximum gain of the IF amplifier in OOK modulation.
0 = No effect
1 = Decreases by 20 dB (typical) the maximum gain of the IF amplifier, in OOK modulation only
The reduction in gain can be observed if the IF amplifier AGC system is disabled (by setting RAGC = 1).
RSSIE (RSSI Enable) enables the RSSI function.
0 = Disabled
1 = Enabled
EDD (Envelop Detector Decay) controls the envelop detector decay.
0 = Slow decay for minimum ripple
1 = Fast decay
RAGC (Reset Automatic Gain Control) resets both receiver internal AGCs.
0 = No action
1 = Sets the gain to its maximum value
MC33596 Data Sheet, Rev. 3
30
Freescale Semiconductor