MICRF505BML datasheet(11/27 Pages) MICREL

11 / 27 page

May 13, 2004

M9999-051304

MICRF505

Micrel

Writing to n Registers having Non-

Incremental Addresses

Registers with non-incremental addresses can be written to

in one write-sequence as well. Example of non-incremental

addresses: “0,1,3”. However, this requires more overhead,

and the user should consider the possibility to make a

“continuous” update, for example, by writing to “0,1,2,3”

(writing the present value of “2” into “2”). The simplest

firmware is achieved by always writing to all registers. Refer

to previous sections.

This write-sequence is divided into several sub-parts:

• Disable the generation of load-signals by clearing

bit “load_en” (bit0 in ControlRegister0)

• Repeat for each group of registers having incre-

mental addresses:

– Bring CS active

– Enter first address for this group, R/W bit and

values

– Bring CS inactive

– Finally, enable and make a load-signal by

setting “load_en”

Refer to the previous sections for how to write to 1 or n (with

incremental addresses) registers in the MICRF505.

Reading from the control registers in

MICRF505

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 MICRF505 (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 a number 1-23.

Reading n registers from MICRF505

Figure 3.

In the figure, 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 MICRF505. MICRF

will change the IO line at positive edges. The user

should read the IO line at the negative edges.

• Bring CS inactive. This will make the IO line an

input to the MICRF505 again

• Make the IO line an output from the user again.

SCLK

RW D7

Address of register i

Data read fromreg. i

IO Input

IO Output

Sample time

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