Maxim-integrated MAXQ622 Manual do Utilizador descarregar pdf (Página 131)

MAXQ612/MAXQ622 User’s Guide

Maxim Integrated 8-7

Figure 8-6. Receive Burst-Count Example

IRRX

2 3

6 84 7

CARRIER FREQUENCY

CALCULATION

IRMT = PULSE COUNTING IRMT = PULSE COUNTING

IRV

IRMT

IRV = CARRIER CYCLE COUNTING

CAPTURE INTERRUPT (IRIF = 1)

IRV ≥ IRMT

IRV = 0 (IF IRXRL = 1)

TO0

SOFTWARE SET IRCA = CARRIER FREQUENCY.

SOFTWARE SETS RXBCNT = 1 (WHICH SETS IRMT = 0001 IN HARDWARE).

SOFTWARE CLEARS IRCFME = 0 SO THAT IRV COUNTS CARRIER CYCLES. IRV IS RESET TO 0 ON QUALIFIED EDGE DETECTION IF IRXRL = 1.

SOFTWARE ADDS TO IRMT THE NUMBER OF PULSES USED FOR CARRIER MEASUREMENT.

IRCA x 2X COUNTER FOR SPACE CAN BEGIN IMMEDIATELY (QUALIFIED EDGE WILL RESET) .

QUALIFIED EDGE DETECTED: IRMT++

IRV RESET TO 0 IF IRXRL = 1.

IRCA x 2 PERIOD ELAPSES: IRIF = 1; CARRIER ABSENCE = SPACE.

BURST MARK = IRMT PULSES.

SOFTWARE CLEARS RXBCNT = 0 SO THAT WE CAPTURE ON THE NEXT QUALIFIED EDGE.

QUALIFIED EDGE DETECTED: IRIF = 1, CAPTURE ≥ IRMT AS THE BURST SPACE (PLUS UP TO ONE CARRIER CYCLE).

SOFTWARE SET RXBCNT = 1 AS IN (5).

CONTINUE (5) TO (8) UNTIL LEARNING SPACE EXCEEDS SOME DURATION. IRV ROLLOVERS CAN BE USED.

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Maxim-integrated MAXQ622 Manual do Utilizador Página 131