MC13201 Technical Data, Rev. 1.1,

Freescale Semiconductor

11

6.2

Serial Peripheral Interface (SPI)

The host microcontroller directs the MC13201, checks its status, and reads/writes data to the device

through the 4-wire SPI port. The transceiver operates as a SPI slave device only. A transaction between

the host and the MC13201 occurs as multiple 8-bit bursts on the SPI. The SPI signals are:

1. Chip Enable (CE) - A transaction on the SPI port is framed by the active low CE input signal. A

transaction is a minimum of 3 SPI bursts and can extend to a greater number of bursts.

2. SPI Clock (SPICLK) - The host drives the SPICLK input to the MC13201. Data is clocked into the

master or slave on the leading (rising) edge of the return-to-zero SPICLK and data out changes

state on the trailing (falling) edge of SPICLK.

NOTE

For Freescale microcontrollers, the SPI clock format is the clock phase

control bit CPHA = 0 and the clock polarity control bit CPOL = 0.

3. Master Out/Slave In (MOSI) - Incoming data from the host is presented on the MOSI input.

4. Master In/Slave Out (MISO) - The MC13201 presents data to the master on the MISO output.

A typical interconnection to a microcontroller is shown in Figure 7.

Table 7. MC13201 Mode Definitions and Transition Times

Mode

Definition

Transition Time

To or From Idle

Off

All IC functions Off, Leakage only. RST asserted. Digital outputs are tri-stated

including IRQ

10 - 25 ms to Idle

Hibernate

Crystal Reference Oscillator Off. (SPI not functional.) IC Responds to ATTN. Data is

retained.

7 - 20 ms to Idle

Doze

Crystal Reference Oscillator On but CLKO output 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) µs to Idle

Idle

Crystal Reference Oscillator On with CLKO output available. SPI active.

Receive

Crystal Reference Oscillator On. Receiver On.

144 µs from Idle

Transmit

Crystal Reference Oscillator On. Transmitter On.

144 µs from Idle