 2009 Microchip Technology Inc.

DS01302A-page 5

AN1302

PC SIDE SOFTWARE

communication channel. The main use for such a boot-

loader is in a multiprocessor system where the main

processor can update the firmware of several proces-

sors in the same system.

We can, however, use PC software if we use a device

software. We used the PICkit™ Serial analyzer

The software is written using Visual C# 2008, Express

Edition. The PC software has the primary function of

importing the hex file, splitting it into smaller packets

and sending the data to the bootloaded device. Read-

ing back program data from the device is also possible.

When designing the firmware for the main processor in

a multiprocessor system, the above software can serve

as a starting point.

FIGURE 3:

PC HOST APPLICATION

WINDOW

To upload a new hex file to the device you must first

open the hex file. This can be done using the Import

Hex command found in the File menu (see Figure 3).

You will notice that the content of the currently loaded

file is displayed in the lower side of the window. Once

the new firmware is loaded, it is ready to be sent to the

target device. This is done by using the Program com-

mand under the Bootloader menu. The programming

operation will consist in a full erase followed by a firm-

ware download. The erase-only operation is available

in the same menu. The firmware can also be read from

the target device using the Read command in the Boot-

loader menu. The program memory data can be saved

into a hex file using the Export Hex command in the File

menu. After a successful firmware download operation,

switching to the application code is done using the Run

firmware command in the Bootloader menu.

CONCLUSION

Using a bootloader is a very efficient way to allow

firmware upgrades in the field. Products can be easily

upgraded to support new features. Fixing code bugs is

also easier.

The bootloader code occupies the lower part of the

program memory between 0x0000 and 0x01FF (512

bytes). The bootloader features interrupt forwarding to

allow applications to use interrupts.

devices can be connected on the same bus, each

device having it's own address.