MC68HC05X4 Datasheet, PDF (17/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Bootloader
routines
Freescale Semiconductor, Inc.
Modes of Operation and Pin Descriptions
Bootloader modes for the MC68HC05X4 and MC68HC705X4
The program in bootloader ROM contains the following routines, which
are accessed through a jump table at the start of the bootloader program
(all routines end with an RTS instruction):
Receive serial byte from user (address: BTROM + 3)
This routine allows a serial byte to be read from PA0. The data read is
written directly into memory, using the index register as an offset from
the address of the first byte of RAM.
Transmit serial byte to user (address: BTROM + 6)
This routine allows the contents of the accumulator to be transmitted via
PA1.
Examine user memory byte (address: BTROM + 9)
This routine reads two bytes from the serial receive pin (RXD). These
are taken to be the upper and lower address bytes of the location to be
examined. The address is then read and transmitted through the serial
transmit pin (TXD).
5-modes
MOTOROLA
Modes of Operation and Pin Descriptions
For More Information On This Product,
Go to: www.freescale.com
MC68HC05X4 Rev 1.0
17