MC33591FTA データシートの表示（PDF） - Motorola => Freescale

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MC33591FTA

PLL Tuned UHF Receiver for Data Transfer Applications

Motorola => Freescale 

CONFIGURATION REGISTERS

bits may lead to unexpected configurations. The first bit transmitted on MOSI does not change the content of the

configuration registers. Note that a low level applied on RESETB does not affect the configuration register

content.

When RESETB is set to a high level, if Data Manager is enabled (DME=1), ROMEO2 becomes master and

sends received data on the MOSI line and the recovered clock on SCLK. It is then recommended that the MCU

SPI is set as slave. If the data received does not fit in an entire number of bytes, the data manager will fill the last

byte. If the data received constitute an whole number of bytes, the data manager may generate and send an

extra byte whose content is irrelevant. If DME=0, the SPI is disabled. Raw data is sent on the MOSI line.

When ROMEO2 SPI is changed from master (run mode) to slave (configuration mode) or from slave to

master, it is recommended that the MCU SPI is set as slave before the mode transition.

At power-on, the POR resets the internal registers. This defines the receiver default configuration (see gray

rows on tables 4, 7 & 8). In this configuration, the SPI is disabled and ROMEO2 sends raw data on the MOSI line.

This default configuration enables the circuit to operate as a standalone receiver without any external control.

After POR, RESETB forces a low level. Therefore an external pull-up resistor should be used in order to avoid

entering configuration mode.

Figure 12: Writing into configuration registers

MCU (master)

0

CR1

CR2

ROMEO2

CR3

MOSI line

Figure 13: Reading configuration registers

MCU (master)

1 Don’t care

Don’t care

ROMEO2

Don’t care

SCLK line

MOSI line

1

CR1

MCU (master)

CR2

CR3

ROMEO2

SCLK line

MISO line

CONFIGURATION REGISTERS

Table 4 describes the Configuration Register 1 (CR1).

Table 4: Configuration Register 1

bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

Bit name

R/W CF MOD SOE SR1 SR0 DME HE

Reset value

1

1

0

1

0

1

0

0

10

MC33591 Technical Data

MOTOROLA

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