MCRF450 datasheet(39/50 Pages) MICROCHIP

39 / 50 page

 2003 Microchip Technology Inc.

DS40232H-page 39

MCRF450/451/452/455

EXAMPLE 9-4:

TO READ DATA FROM THE DEVICE

To read the content of Block 5 that has been programmed in the previous example, the Interrogator sends the following

command:

Calibration pulse + Read Command (‘110’) + Address (‘00101’) + Parity (‘0’)

= Calibration pulse + C50 (hex)

The gap positions in the 1-of-16 PPM signal for the above hex string are:

12 (C), 5 (5), 0 (0).

Device Response:

When the device receives the above Interrogator command, the device outputs the following 70 kHz Manchester

encoded data string (see Section 6.2.2 “Structure of Device Response”):

Preamble (8 bits) + Block number (5 bits, LSB first) + ‘000’ + Block Data (32 bits, LSB first) + SCRC (16 bits)

= 1-1-1-1-1-1-1-0 (f7) + 1-0-1-0-0-0-0-0 (5 0) + 1-1-1-1 0-1-1-1 1-0-1-1... 1-0-0-0

0-0-0-0

(f e d c 3 2 1 0) + 0-1-1-0 0-0-0-0 0-1-0-0 0-1-1-1 (602e).

EXAMPLE 9-5:

TO SEND THE “END PROCESS” COMMAND

The Interrogator command structure (see Section 6.2 “Anti-collision Command Controller”) for the End Process is:

Calibration pulse + End Process Command (‘111’) + Address (‘01010’) + Parity (1) = Calibration pulse + EA1 (hex)

The gap positions in the 1-of-16 PPM signal for the above hex string are:

14 (E), 10 (A), 1 (1).

Device Response:

The device outputs the 8-bit preamble (‘11111110’) when it receives the End Process command, and enters the

Sleeping Loop.

MCRF450 Datasheet(PDF) 39 Page - Microchip Technology