May 13, 2004

9

M9999-051304

MICRF505

Micrel

How to write:

Bring CS active to start a write sequence. The active state of

the CS line is “high.” Use the SCLK/IO serial interface to clock

“Address” and “R/W bit and “Values” into the MICRF505.

MICRF505 will sample the IO line at negative edges of SCLK.

Make sure to change the state of the IO line before the

negative edge. Refer to figures below.

Bring CS inactive to make an internal load-signal and com-

plete the write-sequence. Note: There is an exception to this

point. If the programming bit called “load_en” (bit0 in

ControlRegister0) is “0”, then no load pulse is generated.

The two different ways to “program the chip” are:

• Write to a number of control registers (0-22) when

the registers have incremental addresses (write to

1, all, or n registers)

• Write to a number of control registers when the

registers have non-incremental addresses

Writing to a Single Register

Writing to a control register with address “A6, A5, ... A0” is

described here. During operation, writing to 1 register is

sufficient to change the way the transceiver works. Typical

example: Change from receive mode to power-down.

Field

Comments

Address:

7 bit = A6, A5, ... A0 (A6 = msb, A0 = lsb)

R/W bit:

“0” for writing

Values:

8 bits = D7, D6, ... D0 (D7 = msb, D0 = lsb)

Table 3. ”Address” and “R/W bit” together make 1 octet.

In addition, 1 octet with programming bits is entered. Totally, 2 octets are clocked into the MICRF505.

D0

D1

D2

D6

D7

RW

A0

A5

A6

CS

SCLK

IO

Address of register i RW

Data to write into register i

Internal load pulse made here

Figure 1.

In Figure 1, IO is changed at positive edges of SCLK. The MICRF505 samples the IO line at negative edges. The value of the

R/W bit is always “0” for writing.

Writing to All Registers

After a power-on, all writable registers should be written. This

is described here.

Writing to all registers can be done at any time. To get the

simplest firmware, always write to all registers. The price to

pay for the simplicity is increased write-time, which leads to

increased time to change the way the MICRF505 works.

What to write

Field

Comments

Address:

'0000000' (address of the first register to write to, which is 0)

R/W bit:

“0” for writing

Values:

1st Octet: wanted values for ControlRegister0. 2nd octet: wanted values for ControlRegister1 and so on for all of the

octets. So the 22nd octet wants values for ControlRegister21. Refer to the specific sections of this document for actual

values.

Table 4. “Address” and “R/W bit” together make 1 octet. In addition, 22 octets with programming bits are

entered. Totally, 23 octets are clocked into the MICRF505.

How to write:

• Bring CS high

• Use SCLK and IO to clock in the 2 octets

• Bring CS low