MICRF505BML datasheet(7/27 Pages) MICREL

7 / 27 page

May 13, 2004

M9999-051304

MICRF505

Micrel

Programming

General

The MICRF505 functions are enabled through a number of

programming bits. The programming bits are organized as a

set of addressable control registers, each register holding 8

bits.

There are 23 control registers in total in the MICRF505, and

they have addresses ranging from 0 to 22. The user can read

all the control registers. The user can write to the first 22

registers (0 to 21); the register with address 22 is a read-only

All control registers hold 8 bits and all 8 bits must be written

to when accessing a control register, or they will be read.

Some of the registers do not utilize all 8 bits. The value of an

unused bit is “don’t care.”

The control register with address 0 is referred to as

ControlRegister0, the control register with address 1 is

ControlRegister1 and so on. A summary of the control regis-

ters is given in the table below. In addition to the unused bits

(marked with “-”) there are a number of fixed bits (marked with

“0” or “1”). Always maintain these as shown in the table.

The control registers in MICRF505 are accessed through a 3-

wire interface; clock, data and chip select. These lines are

referred to as SCLK, IO, and CS, respectively. This 3-wire

interface is dedicated to control register access and is re-

ferred to as the control interface. Received data (via RF) and

data to transmit (via RF) are handled by the DataIXO and

DataClk (if enabled) lines; this is referred to as the data

interface.

The SCLK line is applied externally; access to the control

registers are carried out at a rate determined by the user. The

MICRF505 will ignore transitions on the SCLK line if the CS

line is inactive. The MICRF505 can be put on a bus, sharing

clock and data lines with other devices.

All control registers should be initiated (written to) following a

power-on. During operation, however, writing to one register

is sufficient to change the way the transceiver works.

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