MC1321x Reference Manual, Rev. 1.6
Freescale Semiconductor
6-1
Chapter 6
Modem Timer Information
6.1
Event Timer Block
Figure 6-1. Event Timer Block Diagram
The MC1321x contains an internal Event Timer block that manages system timing. A simplified block
diagram is shown in
. The Event Timer consists of a prescaler and a 24-bit counter which
increment whenever the crystal clock is operating. Interrupts to the MCU may be generated when the
“current time” of the counter (et[23:0]) matches several pre-determined values set in registers via SPI write
operations. The current time is accessible at any time via a SPI read operation, as well as, programmable
via a SPI write operation. The Event Timer provides the following functions:
•
Timer to generate current system time
•
Interrupt generation at pre-determined system times
•
Exit from Doze Mode at pre-determined system time
•
Latches “timestamp” value during packet reception
•
Initiates timer-triggered sequences
tmr_prescale[2:0]
16 MHz
Prescale
3
24-Bit Counter
tmr_cmp1[23:0]
tmr_cmp2[23:0]
tmr_cmp3[23:0]
tmr_cmp4[23:0]
= ?
= ?
= ?
= ?
Yes
Yes
Yes
Yes
24
24/16
24
24
24
tmr1_irq
tmr2_irq
tmr3_irq
tmr4_irq
tmr1_mask
tmr2_mask
tmr3_mask
tmr4_mask
Inte
rrupt Logic
tc2_prime[15:0]
Mux
tmr_clk
et[23:0]
Содержание freescale semiconductor MC13211
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Страница 166: ...Modem Modes of Operation MC1321x Reference Manual Rev 1 6 7 22 Freescale Semiconductor...
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Страница 308: ...MCU Timer PWM TPM Module MC1321x Reference Manual Rev 1 6 17 16 Freescale Semiconductor...
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