MC33596_10 Datasheet, PDF (24/70 Pages) Freescale Semiconductor, Inc – PLL Tuned UHF Receiver for Data Transfer Applications

Receive Mode
11.4.2 Operation
Two modes of operation are available: sample mode and continuous mode.
11.4.2.1 Sample Mode
Sample mode allows the peak power of a specific pulse in an incoming frame to be measured.
The quasi peak detector is reset by closing S1. After 7 × T_digclk, S1 is released. S2 is closed when RSSIC
is set high. On the falling edge of RSSIC, S2 is opened. The voltage on RSSIOUT is sampled and held.
The last RSSI conversion results are stored in the RSSI register and no further conversion is done.
The RSSI register is updated every 32 × T_digclk. Therefore, the minimum duration of the high pulse on
RSSIC is 32 × T_digclk.
RSSIC
S1
7 x t_digclk
Closed
Open
Closed
S2 Open
Closed
Open
RSSI Register ^Frozen
Updated
Frozen
RSSIOUT
Sampled and Hold RSSI Voltage
CONFB
Peak Detector
Reset
MOSI
Sampling
CMD
MISO
RSSI Value
Figure 16. RSSI Operation in Sample Mode
11.4.2.2 Continuous Mode
Continuous mode is used to make a peak measurement on an incoming frame, without having to select a
specific pulse to be measured.
The quasi peak detector is reset by closing S1. After 7 × T_digclk, S1 is opened. S2 is closed when RSSIC
is set high. As long as RSSIC is kept high, S2 is closed, and RSSIOUT follows the peak value with a decay
time constant of 5 ms.
The ADC runs continuously, and continually updates the RSSI register. Thus, reading this register gives
the most recent conversion value, prior to the register being read. The minimum duration of the high pulse
on CONFB is 32 × T_digclk.
MC33596 Data Sheet, Rev. 4
24
Freescale Semiconductor