
MC1321x Reference Manual, Rev. 1.0
Freescale Semiconductor
7-1
Chapter 7
Modem Modes of Operation
7.1
Modem Operational Modes Summary
The MC1321x has a number of passive operational modes that allow for low-current operation as well as
modes where the transceiver is active. These modes are summarized, along with the transition times, in
operational modes.
Idle Mode is normally the state from which other states are derived. Low power states include the Off,
Hibernate, and Doze modes. The Off state is the lowest power and is caused by the hardware reset.
Transition from the Off to Idle Mode occurs when RST is negated to high. Once in Idle Mode, the SPI is
active and used to control the MC1321x. Transition to Hibernate or Doze modes is enabled via the SPI.
There are active states of Idle, Transmit (TX), Receive (RX), and Clear Channel Assessment (CCA)
modes. The transition from the Idle state to the TX or RX is first determined by the desired data mode of
the user, i.e., Packet Mode or Stream Mode. If Packet Data Mode is used, writing to the xcvr_seq field can
select RX or TX in Packet Mode. Packet RX and TX can also be modified as timer-based sequences using
without and with timer-initiated sequences.
If Stream Data Mode is used, then the configuration bits of tx_strm, rx_strm, and use_strm_mode control
transition to the TX and RX sequences. Use_strm_mode is a top level control bit and enables a sequence
Table 7-1. Modem Mode Definitions and Transition Times
Mode
Definition
Transition
Time
Off
RST asserted. All IC functions Off, Leakage only. Digital outputs are tri-stated including
IRQ. Any RAM buffer data is lost.
10 - 25 ms to
Idle
Hibernate
Crystal Reference Oscillator Off. SPI not functional. IC Responds to ATTN. Data is
retained.
8 - 20 ms to Idle
Doze
Crystal Reference Oscillator On but CLKO is available only if Register 7, Bit 9 = 1 for
frequencies of 1 MHz or less. (SPI not functional.) Responds to ATTN and can be
programmed to enter Idle Mode through an internal timer comparator.
(300+1/CLKO)
s to Idle
Idle
Crystal Reference Oscillator On with CLKO output available. SPI active.
Receive
Crystal Reference Oscillator On. Receiver On.
144 s from Idle
Transmit
Crystal Reference Oscillator On. Transmitter On.
144 s from Idle
CCA / Energy
Detect
Crystal Reference Oscillator On. Receiver On.
144 s from Idle