Modem Timer Information
MC1321x Reference Manual, Rev. 1.6
6-6
Freescale Semiconductor
2. Enable the timer compare interrupt mask.
3. Read the “current time” value from et[23:0].
4. Add an offset to this value to equal desired “future time”.
5. Program the appropriate timer_compare value to “future time”.
6. Program the appropriate tmr_cmpx_dis bit to enable the compare.
7. Allow a timer compare match to set the status register bit and generate an interrupt. The appropriate
internal status register bit is always set upon a timer_compare match. An external interrupt is
generated when the corresponding SPI interrupt mask bit, Register 5, Bits 3, 2, 1, or 0, is set.
8. Program the appropriate tmr_cmpx_dis bit to disable the compare function. If this is not done, the
compare function will continue to run and generate another interrupt every time the counter rolls
over and again matches the comparator.
6.7.2
Using tmr_cmp2[23:0] to Exit Doze Mode
The Event Timer provides a timer-based mechanism to bring the MC1321x out of Doze Mode. The
MC1321x is put into Doze Mode when doze_en, Control_B Register 07, Bit 0, is programmed high. While
in Doze Mode, a match between “current time” and field tmr_cmp2[23:0] causes the MC1321x to exit
Doze Mode and return to Idle Mode.
The general procedure is as follows:
1. Read the “current time” value from et[23:0].
2. Add an offset to this value to equal desired “future time” to exit Doze Mode.
3. Program field tmr_cmp2[23:0] to value “future time”.
4. Program doze_mask, Register 05, Bit 4, to 1.
5. Program doze_en, Register 7, Bit 0, to 1. The MC1321x then enters Doze Mode.(Note that the
control bit tmr_cmp2_dis has no effect on this mode).
6. When “current time” equals tmr_cmp2[23:0], the MC1321x exits Doze Mode, and doze_irq,
Register 24, Bit 9, gets set. An external interrupt is also generated because doze_mask is set.
NOTE
The MC1321x can always be taken out of Doze Mode by asserting ATTN
or RST. Also, if acoma_en IRQ_Mask Register 05, Bit 8 is set before
entering Doze Mode, the Event Timer logic is disabled for additional power
savings and only ATTN or RST will cause exit of Doze Mode.
6.7.3
Timer-Triggered Transceiver Events
An Event Timer can be used to initiate the MC1321x transceiver operations such as transmit and receive.
The desired operation can be scheduled to commence at a future time greater than the “current time” by
using the MC1321x timer-triggered operation capability. Timer-triggered operations are invoked by using
either by tmr_cmp2 [23:0] for Packet Mode operations or tc2_prime[15:0] for Stream Mode operations. A
time greater than the “current time” is programmed into the appropriate compare field and tmr_trig_en,
Control_A Register 6, Bit 7 is programmed high. When the “current time” advances to match the value set
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