Micrel, Inc.

MICRF600

September 2005

9

M9999-091905

How to write:

•

Bring CS high

•

Use SCLK and IO to clock in the 23 octets

•

Bring CS low

Refer to the figure in the next section, “Writing to n

registers having incremental addresses”.

Writing to n Registers Having Incremental Addresses

In addition to entering all bytes, it is also possible to enter

a set of n bytes, starting from address i = “A6, A5, … A0”.

Typical example: Clock in a new set of frequency dividers

(i.e. change the RF frequency). “Incremental addresses”.

Registers to be written are located in i, i+1, i+2.

What to write:

Field

Comments

Address:

7 bit = A6, A5, …A0 (A6 = msb. A0 = lsb) (address of first byte to

write to)

R/W bit:

“0” for writing

Values:

n* 8 bits =

D7, D6, …D0 (D7 = msb, D0 = lsb) (written to control reg. with

address ”i”)

D7, D6, …D0 (D7 = msb, D0 = lsb) (written to control reg. with

address ”i+1”)

D7, D6, …D0 (D7 = msb, D0 = lsb) (written to control reg. with

address ”i+n-1”)

Table 5. “Address” and “R/W bit” together make 1 octet

In addition, n octets with programming bits are entered.

Totally. 1 +n octets are clocked into the MICRF600.

How to write:

•

Bring CS high

•

Use SCLK and IO to clock in the 1 + n octets

•

Bring CS low

In Figure 1, IO is changed at positive edges of SCLK. The

MICRF600 samples the IO line at negative edges. The

value of the R/W bits is always “0” for writing.

CS

SCLK

IO

A6

A5

A0

RW

D7

D6

D2

D1

D0

Address of first

RW

register to write to,

register i

Data to write

into register i

Internal load pulse made here

Data to write

into register i+1

Figure 2. How to write to many Control Registers

Reading from the Control Registers in MICRF600

The “read-sequence” is:

1. Enter address and R/W bit

2. Change direction of IO line

3. Read out a number of octets and change IO

direction back again.

It is possible to read all, 1 or n registers. The address to

read from (or the first address to read from) can be any

valid address (0-22). Reading is not destructive, i.e. values

are not changed. The IO line is output from the MICRF600

(input to user) for a part of the read-sequence. Refer to

procedure description below.

A read-sequence is described for reading n registers,

where n is number 1-23.

Reading n Registers from MICRF600

CS

SCLK

IO

A6

A5

A0

RW D7

D6

D0

Address of register i

RWData read from reg. i

Simple time

IO Input

IO Output

Figure 3. How to read from many Control Registers

In Figure 3, 1 register is read. The address is A6, A5, …

A0. A6 = msb. The data read out is D7, D6, …D0. The

value of the R/W bit is always “1” for reading.

SCLK and IO together form a serial interface. SCLK is

applied externally for reading as well as for writing.

•

Bring CS active

•

Enter address to read from (or the first address to

read from) (7 bits) and

•

The R/W bit = 1 to enable reading

•

Make the IO line an input to the user (set pin in

tristate)

•

Read n octets. The first rising edge of SCLK will

set the IO as an output from the MICRF600.

MICRF will change the IO line at positive edges.

The user should read the IO line at the negative

edges.

•

Make the IO line an output from the user again.