MC68HC11E0CFNE3 Datasheet, PDF (211/242 Pages) Freescale Semiconductor, Inc – M68HC11E Family

Errors: None
Labels: 28
Last Program Address: $B67C
Last Storage Address: $0000
Program Bytes: $007D 125
Storage Bytes: $0000 0
Driving Boot Mode from a Personal Computer
Driving Boot Mode from a Personal Computer
In this example, a personal computer is used as the host to drive the bootloader of an MC68HC711E9.
An M68HC11 EVBU is used for the target MC68HC711E9. A large program is transferred from the
personal computer into the EPROM of the target MC68HC711E9.
Hardware
Figure 7 shows a small modification to the EVBU to accommodate the 12-volt (nominal) EPROM
programming voltage. The XIRQ pin is connected to a pullup resistor, two jumpers, and the 60-pin
connectors, P4 and P5. The object of the modification is to isolate the XIRQ pin and then connect it to the
programming power supply. Carefully cut the trace on the solder side of the EVBU as indicated in Figure
7. This disconnects the pullup resistor RN1 D from XIRQ but leaves P4–18, P5–18, and jumpers J7 and
J14 connected so the EVBU can still be used for other purposes after programming is done. Remove any
fabricated jumpers from J7 and J14. The EVBU normally has a jumper at J7 to support the trace function
Figure 8 shows a small circuit that is added to the wire-wrap area of the EVBU. The 3-terminal jumper
allows the XIRQ line to be connected to either the programming power supply or to a substitute pullup
resistor for XIRQ. The 100-ohm resistor is a current limiter to protect the 12-volt input of the MCU. The
resistor and LED connected to P5 pin 9 (port C bit 0) is an optional indicator that lights when programming
is complete.
Software
BASIC was chosen as the programming language due to its readability and availability in parallel versions
on both the IBM^® PC and the Macintosh^®. The program demonstrates several programming techniques
for use with an M68HC11 and is not necessarily intended to be a finished, commercial program. For
example, there is little error checking, and the user interface is elementary. A complete listing of the
BASIC program is included in Listing 2. BASIC Program for Personal Computer with moderate comments.
The following paragraphs include a more detailed discussion of the program as it pertains to
communicating with and programming the target MC68HC711E9. Lines 25–45 initialize and define the
variables and array used in the program. Changes to this section would allow for other programs to be
downloaded.
® _{IBM is a registered trademark of International Business Machines.}
® _{Macintosh is a registered trademark of Apple Computers, Inc.}
M68HC11 Bootstrap Mode, Rev. 1.1
Freescale Semiconductor
211