UHF ASK/FSK Receiver ATA3745 - Atmel Corporation

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Figure 5-9. Debouncing of the Demodulator Output Dem_out DATA Lim_min ≤ CV_Lim < Lim_max t min1 t ee CV_Lim < Lim_min or CV_Lim ≥ Lim_max t min2 t ee Figure 5-10. Steady L State Limited DATA Output Pattern after Transmission Enable IC Bit check Dem_out DATA Sleep mode Bit-check mode Receiving mode t min2 t DATA_L_max After the end of a data transmission, the receiver remains active and random noise pulses appear at pin DATA. The edge-to-edge time period t ee of the majority of these noise pulses is equal to or slightly higher than T DATA_min . 5.4.2 Switching the Receiver Back to Sleep Mode The receiver can be set back to polling mode via pin DATA or via pin ENABLE. When using pin DATA, this pin must be pulled to low for the period t1 by the connected microcontroller. Figure 5-11 on page 17 illustrates the timing of the OFF command (see also Figure 5-15 on page 22). The minimum value of t1 depends on the BR_Range. The maximum value for t1 is not limited, but it is recommended not to exceed the specified value to prevent erasing the reset marker. This item is explained in more detail in “Configuration of the Receiver” on page 18. Setting the receiver to sleep mode via DATA is achieved by programming bit 1 of the OPMODE register to “1”. Only one synchronous pulse (t3) is issued. The duration of the OFF command is determined by the sum of t1, t2 and t10. After the OFF command, the sleep time T Sleep elapses. Note that the capacitive load at pin DATA is limited. The resulting time constant t together with an optional external pull-up resistor should not be exceeded, to ensure proper operation. If the receiver is set to polling mode via pin ENABLE, an "L" pulse (T Doze ) must be issued at that pin. Figure 5-12 on page 17 illustrates the timing of that command. After the positive edge of this pulse, the sleep time T Sleep elapses. The receiver remains in sleep mode as long as ENABLE is held to "L". If the receiver is polled exclusively by a microcontroller, T Sleep can be programmed to “0” to enable an instantaneous response time. This command is the faster option than via pin DATA, at the cost of an additional connection to the microcontroller. 16 ATA3745 4901B–RKE–11/07
ATA3745 Figure 5-11. Timing Diagram of the OFF Command Via Pin DATA t 1 t 2 t 3 t 5 t 4 t10 Out1 (microcontroller) t7 DATA (ATA3745) X X Serial bi-directional data line X X Receiving mode Bit 1 ("1") (Start Bit) T Sleep Start-up mode OFF command Figure 5-12. Timing Diagram of the OFF Command Via Pin ENABLE t off T Doze T Sleep Startup mode ENABLE DATA (ATA3745) X X Serial bi-directional data line X Receiving mode X 17 4901B–RKE–11/07
Page 1 and 2: Features • Supply Voltage 4.5V to
Page 3 and 4: ATA3745 2. Pin Configuration Figure
Page 5 and 6: ATA3745 To determine f LO , the con
Page 7 and 8: ATA3745 4. Analog Signal Processing
Page 9 and 10: ATA3745 5. Polling Circuit and Cont
Page 11 and 12: ATA3745 5.2.1 Sleep Mode The length
Page 13 and 14: ATA3745 5.3 Bit Check Mode In bit c
Page 15: ATA3745 5.3.2 Duration of the Bit C
Page 19 and 20: ATA3745 Table 5-3. Baud1 Effect of
Page 21 and 22: ATA3745 5.5.1 Conservation of the R
Page 23 and 24: ATA3745 6. Absolute Maximum Ratings
Page 25 and 26: ATA3745 8. Electrical Characteristi
Page 27 and 28: ATA3745 9. Electrical Characteristi
Page 29 and 30: ATA3745 10. Ordering Information Ex

UHF ASK/FSK Receiver ATA3745 - Atmel Corporation

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