MC68HC705J2 Datasheet, PDF (47/82 Pages) Freescale Semiconductor, Inc – member of the low-cost

Freescale Semiconductor, Inc.
1
SECTION 8
2
BOOTLOADER MODE
3
This section describes how to use the bootloader ROM to download to the on-chip
EPROM.
4
5
8.1 Bootloader ROM
The bootloader ROM, located at addresses $0F01–$0FEF, contains routines for
6
copying to the on-chip EPROM from an external EPROM or from a personal
computer.
7
In MC68HC705J2 native mode, the bootloader copies to the 2 Kbyte space located
at EPROM addresses $0700–$0EFF, the MOR byte at location $0F00, and the user
8
vector addresses $0FF0–$0FFF. In MC68HC05J1 emulation mode, the bootloader
copies to the 1 Kbyte space located at EPROM addresses $0300–$06FF, the MOR
9
byte at location $0700, and the user vector addresses $07F0–$07FF. The addresses
of the copied code must correspond to the internal addresses to which the code is
10
copied. The bootloader ignores all other addresses.
The COP timer is automatically disabled in bootloader mode.
11
8.1.1 External EPROM Downloading
12
Figure 8-1 shows the circuit used to download to the on-chip EPROM from a 2764
13
EPROM. The bootloader circuit includes an external 12-bit counter to address the
EPROM containing the code to be copied.
14
Operation is fastest when unused external EPROM addresses contain $00.
15
16
17
18
19
20
BOOTLOADER MODE
Rev. 2
8-1
For More Information On This Product,
Go to: www.freescale.com