Motorola MC68328 Información técnica descargar pdf (Pagina 25)

Software Development

FLEX System Software

FLEX Alphanumeric Chip MC68175 Interface

3-7

FLEX Alphanumeric Chip is still in Reset or Disable mode. In this case, the

product engineer should check the configuration of the SPI communication

module on the host. Common faults include the SPI module not being

properly enabled or not transmitting properly, the SPI baud-rate being too

high, or the reset line connected to the FLEX Alphanumeric Chip being held

low.The very first packet sent from the host processor to the FLEX

Alphanumeric Chip is a null packet (i.e., a packet of value 0). If this packet is a

nonzero packet, the FLEX One-Way Stack may not calculate the checksum

packet correctly, resulting in a locked-up situation where the chip will never

come out of Reset state. Therefore, the host software may need to initialize the

gSecurity variable to 0 before running FLEX One-Way Stack.

3.1.4 FLEX Alphanumeric Chip and FLEX One-Way Stack

Configurations

The FLEX One-Way Stack software on the host MPU is responsible for configuring the

FLEX Alphanumeric Chip IC by sending to it (via SPI) a series of configuration packets.

The chip needs information such as receiver control, frame assignments, and user

address enabling, so that it behaves properly for a particular paging application. FLEX

One-Way Stack software performs this task automatically after the chip is enabled via

the checksum feature as described above. However, product engineers need to specify

how they would like to configure the chip, and translate those configurations into 32-bit

packets of data that FLEX One-Way Stack will send to the FLEX IC. These configuration

packets are stored in the initialization buffer.

When incorporating FLEX One-Way Stack software into FLEX paging products, it is

important that product engineers properly set up the initialization buffer. The

initialization buffer contains not only configuration data to be sent to FLEX

Alphanumeric Chip but also memory reservations and all necessary setups so that FLEX

One-Way Stack can properly manage and filter paging messages. The initialization

buffer is often in EEPROM, or nonvolatile memory. The initialization data is segmented

by functionality and is divided into four segments: Driver Initialization, Notification,

Message Manager, Filter and FLEX Alphanumeric Chip Initialization segments. Each

segment contains a header block and a data block. The header block in all segments has

the same format as the INIT_SECTION structure defined in

init.h.

The data blocks for

each segment are defined in

struct.h

. A sample of the function that sets up the

initialization buffer is provided in file

idata.c

in FLEX One-Way Stack software.

Frees

cale Semiconductor,

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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