DM163025 Microchip Technology, DM163025 Datasheet - Page 30

• Manufacturer Part Number: DM163025
• Description: PIC DEM FULL SPEED USB DEMO BRD
• Manufacturer: Microchip Technology

Specifications of DM163025

• Main Purpose: Interface, USB 2.0 Host/Controller
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: PIC18F2455/2550/4455/4550
• Primary Attributes: Full Speed (12Mbps)
• Secondary Attributes: MPLAB ICE 2000/4000 Emulator Interface, Temp Sensor, Expansion and PICtail Headers
• Processor To Be Evaluated: PIC18F4550
• Interface Type: RS-232, USB
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18F4xxx
• Kit Contents: Demo Board, Cables, CD & Documents
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: Q2086254

DS51526B-page 26
™
FIGURE 3-6:
When a file is loaded, either from a device or a file, the bootloader demo software also
parses the file to determine if code is available for the different memory areas. If a
device is programmed with that file, only those memory areas with code present are
programmed; the other memory areas are left unchanged. For example, a hex file that
is missing data for the data EEPROM or Configuration Words will only program the
target device’s program memory and user ID spaces; the existing configuration and
stored EEPROM information will be preserved.
3.5.5
The bootloader operates as a separate entity, which means that an application can be
developed with very little concern about what the bootloader is doing. This is as it
should be; the bootloader should be dormant code until an event initiates its operation.
Ideally, bootloader code should never be running during an application’s intended
normal operation.
When developing an application with a resident bootloader, some basic principles must
be kept in mind:
3.5.5.1
When writing in assembly, the boot block and new vectors must be considered. For
modular code, this is usually just a matter of changing the linker script file for the
project. An example is shown in Example 3-1. If an absolute address is assigned to a
code section, the address must point somewhere above the boot block.
For those who write absolute assembly, all that is necessary is to remember that the
new Reset vector is at 800h, and the interrupt vectors are at 808h and 818h. Except for
the bootloader, no code should reside in the boot block area.
Writing Application Code with the Bootloader
WRITING IN ASSEMBLY
CONFIGURATION CONFLICT WARNING DIALOG WITH
TYPICAL DIAGNOSTIC MESSAGE
© 2008 Microchip Technology Inc.