MAXQ61HX-0000+ MAXIM [Maxim Integrated Products], MAXQ61HX-0000+ Datasheet - Page 15

• Manufacturer Part Number: MAXQ61HX-0000+
• Description: 16-BIt Microcontroller with Infrared Module
• Manufacturer: MAXIM [Maxim Integrated Products]

Figure 6. Receive Burst-Count Example
ever two IRCA cycles elapse without getting a qualified
edge. The IRIF interrupt flag thus denotes absence of
the carrier and the beginning of a space in the receive
signal. When the RXBCNT bit is changed from 0 to 1,
the IRMT register is set to 0001h. The IRCFME bit is still
used to define whether the IRV register is counting sys-
tem IRCLK clocks or IRCA-defined carrier cycles. The
IRXRL bit is still used to define whether the IRV register
is reloaded with 0000h on detection of a qualified edge
(per the IRXSEL[1:0] bits). Figure 6 and the descriptive
sequence embedded in the figure illustrate the expect-
ed usage of the receive burst-count mode.
1
TO
IRMT
IRRX
IRV
4
5
6
7
8
9
16-Bit Microcontroller with Infrared Module
CAPTURE INTERRUPT (IRIF = 1).
IRV ≥ IRMT.
IRV = 0 (IF IRXRL = 1).
SOFTWARE SETS IRCA = CARRIER FREQUENCY.
SOFTWARE SETS RXBCNT = 1 (WHICH CLEARS 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 RESETS).
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 IRV ≥ 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.
CARRIER FREQUENCY
CALCULATION
1
______________________________________________________________________________________
2
3
4
5
6
IRMT = PULSE COUNTING
7
IRV = CARRIER CYCLE COUNTING
The MAXQ61H provides two timers/counters that sup-
port the following functions:
• 16-bit timer/counter
• 16-bit up/down autoreload
• Counter function of external pulse
• 16-bit timer with capture
• 16-bit timer with compare
• Input/output enhancements for pulse-width modulation
• Set/reset/toggle output state on comparator match
• Prescaler with 2n divider (for n = 0, 2, 4, 6, 8, 10)
16-Bit Timers/Counters
IRMT = PULSE COUNTING
8
9
15