AN2497 Freescale Semiconductor / Motorola, AN2497 Datasheet - Page 3

• Manufacturer Part Number: AN2497
• Description: HCS08 Background Debug Mode versus HC08 Monitor Mode
• Manufacturer: Freescale Semiconductor / Motorola

MOTOROLA
Communication Protocol
Table 1. Differences Between HC08 Monitor Mode and HCS08 Background Debug Mode
Communication Pin
Firmware/Hardware
Mode Entry
HCS08 Background Debug Mode versus HC08 Monitor Mode
switched to the active background mode instead of executing the SWI
instruction. The BDC also allows access to the on-chip debug module (DBG)
that includes two more 17-bit comparators for more flexible debugging.
The single-wire background interface pin (BKGD) on HCS08 devices is
designated as the mode entry and serial communication pin. Since no other
pins are used for active background mode entry, none of the MCU pin functions
have any limitations.
The BDC has a total of 30 background commands. The CPU registers can be
directly accessed by the commands. Some commands can be performed not
only in the active background mode but also while the user program is running.
Since the BDC uses hardware logic and has a variety of commands, the
HCS08 debugger can support real-time debugging (in conjunction with the
DBG module) and provide a more flexible debugging environment.
In HCS08 devices, the BDC is also used for device tests. There are no other
special test modes as on the HC08. To support the bus state analyzer function
in an emulator, the HCS08 Family has an on-chip debug system (DBG) in
addition to the BDC. This system can capture address or data bus information
by setting one of nine trigger modes. In effect, a small bus state analyzer
function is built into the MCU, so none of the I/O pins are lost to this function.
The details of the DBG function will not be discussed in this note. For more
details, refer to the HCS08 Family Reference Manual (HCS08RMv1/D).
Table 1
HCS08 BDM.
Freescale Semiconductor, Inc.
At least 4 I/O pins required
High voltage required on IRQ pin
Firmware embedded in ROM
General-purpose I/O pin
RS232 type serial (NRZ)
Standard PC communication rates
For More Information On This Product,
shows the summary of the differences between HC08 monitor and
HC08 Monitor Mode
Go to: www.freescale.com
Differences Between HC08 Monitor Mode and HCS08 BDM
Only BKGD pin required
No high voltage required
Hardware module
BDC registers not in user map
Dedicated pin (BKGD pin)
Custom serial protocol
Faster and more speed tolerance
Software or hardware handshake
HCS08 Background Debug Mode
protocol supported
AN2497/D
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