Modem Timer Information
MC1321x Reference Manual, Rev. 1.6
Freescale Semiconductor
6-7
in the compare field, the selected operation sequence will commence automatically without intervention
from the host. This allows the host to arm the MC1321x to execute a desired operation at a future time,
and go off to perform other necessary system functions.
6.7.3.1
Packet Mode Timer_Triggered TX or RX Events
In Packet Mode only tmr_cmp2 [23:0] can be used to initiate a transceiver event. The general procedure
is as follows:
1. Desired frequency must be programmed.
2. If not already low, the MCU sets RXTXEN low.
3. Stream Mode rx_strm, tx_strm, and use_strm_mode control bits must be cleared.
4. Read the “current time” value from et[23:0].
5. Add an offset to this value to equal desired “future time” to initiate selected operation.
6. Program field tmr_cmp2[23:0] to value “future time”.
7. Program tmr_cmp2_dis to 0 to enable the compare function.
8. If desired, program tmr2_mask, IRQ_Mask Register 05, Bit 1 high to enable an interrupt when the
timer compare function completes and starts the transceiver.
9. For a TX operation only, load tx_pkt_length[6:0] and payload data into tx_pkt_RAM[15:0].
10. Program tmr_trig_en, Control_A Register 6, Bit 7 high to enable a timer-based operation.
11. Program the MC1321x/193 for the desired transceiver operation via xcvr_seq[1:0].
12. Assert the RXTXEN pin and hold high.
13. When “current time” equals tmr_cmp2[23:0], the MC1321x initiates the selected transceiver
operation. When tmr2_irq, IRQ_Status Register 24, Bit 2 is set to 1, an external interrupt is
generated if the interrupt mask bit (tmr2_mask) was set high.
NOTE
tmr_trig_en is level sensitive. It is not necessary to program it to 0 prior to
the next timer triggered operation.
14. Once started, the transceiver operation commences in a normal manner.
6.7.3.2
Stream Mode Timer_Triggered TX or RX Events
In Stream Mode, tc2_prime[15:0] is used in place of tmr_cmp2 [23:0] to initiate a transceiver event. The
tmr_cmp2_dis bit must be enabled as allows tc2_prime[15:0] to function. The general procedure is as
follows:
1. Desired frequency must be programmed.
2. If not already low, the MCU sets RXTXEN low.
3. Packet Mode xcvr_seq[1:0] field should be cleared.
4. Read the “current time” value from et[23:0].
5. Add an offset to this value to equal desired “future time” to initiate selected operation.
Note that only the lowest 16 bits are used with tc2_prime[15:0].
Содержание freescale semiconductor MC13211
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