Datasheet

MRF49XA

FIGURE 3-16: TX REGISTER USAGE

FIGURE 3-17: MULTIPLE BYTE WRITE WITH TRANSMIT REGISTER

SPI

Commands

GENCREG PMCREG

TX Latch TX Latch

PMCREG GENCREG

TXDEN = 1

TX Byte 1

Dummy

TX Byte

TXCEN = 0 TXDEN = 0TXCEN = 1

Synt.

Ttx_xtal_on

(1)

TXCEN

Enable

Synthesizer/PA

0xAA

Fraction of the dummy byte

0xAA TX Byte1

TX Data

SDO

(2)

Do not switch the TXCEN off here, because the TX

Byte 1 is not transmitted out, it is only stored in the

internal register

Enabling the transmitter preloads the TX latch with

0xAAAA

(CS, SCK, SDI)

Note 1: Ttx_xtal_on is the start-up time of PLL + PA with a running crystal oscillator.

2: SDO is a tri-state of CS.

IRO

* The device is in Transmit (TX) mode when the RXCEN bit is cleared using the PMCREG.

Transmit Register Write

TX BYTE 1

TX BYTE 2

TX BYTE n

SDO

(Register interrupt in TX mode*)

SCK

SDI