Specifications

Developer’s Serial Bootloader, Rev. 13
MCU slave software
Freescale Semiconductor56
8.9 MC68HC908AP
MC68HC908AP devices are members of the M68HC08 Family that have two SCIs (the SCI channel must
be selected at compile time). MC68HC908AP MCUs have ROM on-chip FLASH programming routines
available. The calling convention is slightly different from other M68HC08s (same as MC68HC908LJ
devices).
Because of the internal oscillator’s simplicity, it does not have the accuracy and stability of the RC
oscillator or the XTAL oscillator. Therefore, the internal oscillator is not suitable if an accurate bus clock
is required and it should not be used as the bus clock source.
A low-cost 32.768 kHz crystal was selected as default source clock for bootloader and user application.
Because the frequency of the crystal is known, no calibration is performed, which saves MCU memory.
Therefore, these MCUs use the Known MCU communication speed method.
8.10 MC68HC908AB/AS/AZ
MC68HC908AB/AS/AZ devices are members of the M68HC08 Family that also have EEPROM memory.
This code also demonstrates the way to program these EEPROM cells using AUTO (automatic clear of
EEPGM) mode.
Since the memory map is not continuous, FC protocol version 3 needs to be used (it allows the “holes” in
the memory map, that is, several separate memory blocks).
8.11 MC9S08GB/GT
MC9S08GB/GT devices are the first members of the HCS08 Family. Because of different hardware
features and FLASH memory allocation, another version of the protocol was required. The protocol is
detected automatically by the latest hc08sprg.exe PC Bootloader software and becomes invisible to
the user.
MC9S08GB/GT MCUs have two SCIs (the SCI channel must be selected at compile time).
These MCUs have no on-chip FLASH programming routines. Therefore, the bootloader must do all
FLASH programming, and this implementation demonstrates this (it has been entirely adopted from
HCS08 Family Reference Manual Volume 1 (Freescale Semiconductor order number HCS08RMv1/D; see
References).
8.12 MC68HC908JW
The HC908JW family has a built-in USB 2.0 Full Speed module. This allows a direct connection via a true
USB interface with the PC. As described in AN3153: Using the Full-Speed USB Module on the
MCHC908JW32 application note, the emulation of the serial COM port can be easily designed. This way,
a fully compatible bootloader (written in C) for the JW32 family has been designed. Once the bootloader
is programmed into the JW32 device, the user code can be reprogrammed anytime using a native USB
connection (serial COM port emulation in Windows).
The installation and usage details are documented in ZSTARRM: Wireless Sensing Triple Axis Reference
design, chapter 5.5 and 6.1.2, out of which the JW32 USB bootloader has been derived. The PC drivers