© 2007 Microchip Technology Inc. DS01094A-page 1
AN1094
INTRODUCTION
The bootloader for dsPIC30F/33F and PIC24H/24F
devices is used to load and run your application on the
target device. The bootloader consists of two
applications:
• Target side bootloader application which must be
programmed into dsPIC30F/33F or PIC24F/24H
program memory prior to bootloader operation.
• Host PC bootloader application which
communicates with the target side bootloader.
The bootloader parses the program HEX file and then
copies it into the appropriate program and EEPROM
memory (if present) on the target device via the
communication channel (UART, CAN, etc.). Figure 1
illustrates this process.
SYSTEM CONCEPT
The bootloader target application is located in the
dedicated program memory region, starting at address
0x100 (for dsPIC30F devices) or 0x400 (for all other
device families). On start-up, the bootloader reads pro-
gram memory address 0x600 (for dsPIC30F family) or
address 0xC00 (for all other device families), which
contains a bootloader delay value. If the bootloader
fails to detect UART activity within the time period spec-
ified by the delay value, it suspends itself and transfers
execution to the user application located at program
memory address 0x602 (for dsPIC30F family) or
address 0xC02 (for all other families). On the other
hand, if the bootloader detects UART activity before it
suspends itself, it programs both EEPROM (if present)
and program memories with the data it receives from
the bootloader host application via UART interface.
The bootloader host application parses the HEX file
containing the user application (generated by
MPLAB
®
IDE) and sends this data to the bootloader
target application via UART. The bootloader host
application also supports additional features, such as
read of program and EEPROM memories.
FIGURE 1: BOOTLOADER PROCESS
Author: Leonard Elevich and Veena Kudva
Microchip Technology, Inc.
IVT/AIVT
Program Flash
EEPROM
Configuration
Registers
Bootloader
Communication Channel
(CAN, UART, etc.)
Bootloader
Communication Channel
(CAN, UART, etc.)
User
Appl
1
2
Target dsPIC
®
or PIC24 Device
3
Host PC (running MPLAB
®
IDE)
1. Bootloader host program reads user application.
2. Bootloader transfers user application to target device (via communication channel).
3. Bootloader target program loads user application into target device memory.
Bootloader for dsPIC30F/33F and PIC24F/24H Devices
