MC33596_10 Datasheet, PDF (21/70 Pages) Freescale Semiconductor, Inc – PLL Tuned UHF Receiver for Data Transfer Applications

Receive Mode
received, output data are complemented also. When an EOM occurs before the current byte is fully
shifted out, dummy bits are inserted until the number of shifted bits is a multiple of 8.
For all states: At any time, a low level applied to STROBE puts the circuit into state 20, and a low level
applied to CONFB forces the state machine to state 1, configuration mode.
11.2.4.3 Timing Definition
As shown in Figure 13, a settling time is required when entering the on state.
Receiver
Status
Off
On
Ton
RF
Signal
Off
On
Toff
Setting
Time
ID ID ID ID ID ID ID ID ID _{Header Data EOM}
ID
Detected
Figure 13. Receiver Usable Window
The goal for the receiver is to recognize at least one ID during Ton time. Many IDs are transmitted during
that time.
During Ton, the receiver should be able to detect an ID, but as receiver and transmitter are not
synchronized, an ID may already be transmitted when Ton time begins. That is the reason why Ton should
be sized to receive two IDs: to be sure to recognize one, no matter what the time difference between
beginning of transmission of the ID and beginning of run time for the receiver.
Ton should also include the setting time of the receiver. Setting time is composed of the crystal oscillator
wakeup time¹, the PLL lock time², and setup of all analog parameters³ (AGC and demodulator need some
time to settle).
Toff should be sized to allow the positioning of an on state during the transmission of the ID field.
During the setting time, no reception is possible.
11.3 Receiver On/Off Control
In receive mode, on/off sequencing can be controlled internally using the strobe oscillator, or managed
externally by the MCU through the input pin STROBE.
If the strobe oscillator is selected (SOE = 1):
• Off time is clocked by the strobe oscillator
• On time is clocked by the crystal oscillator, enabling accurate control of the on time, and therefore
of the current consumption of the whole system
1. Refer to parameter 5.10 found in Section 19.4, “PLL & Crystal Oscillator.”
2. Refer to parameter 5.9 found in Section 19.4, “PLL & Crystal Oscillator.”
3. Refer to preamble definition found in Figure 9.
MC33596 Data Sheet, Rev. 4
Freescale Semiconductor
21