MC68HC05X4 Datasheet, PDF (19/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Modes of Operation and Pin Descriptions
Bootloader modes for the MC68HC05X4 and MC68HC705X4
EPROM containing the user code are incremented independently it is
essential that the data layout in the 2764 EPROM conforms exactly to
the MC68HC705X4 memory map.
The bootloader uses an external 12-bit counter with a clock and a reset
function to address the memory device containing the code to be copied.
The 12-bit counter can address up to 4K bytes of memory therefore a
port pin must be used to address the additional memory space.
NOTE: In bootloader mode the device will always default to the divide-by-10
option for the oscillator division ratio.
EPROM
programming
register
All necessary manipulation of this register is carried out automatically by
the bootloader routine.
Address: $1G00
Bit 7
6
5
4
3
2
1
0
0
0
0
0
ELAT
0
Reset: 0
0
0
0
0
0
0
Figure 3. EPROM Programming Register (EPROG)
Bit 0
EPGM
0
ELAT — EPROM address and data latch
1 = Configures EPROM address and data buses for programming.
0 = Configures EPROM address and data buses for normal
operation.
EPGM — EPROM programming power control
1 = Switches EPROM programming power on.
0 = Switches EPROM programming power off.
A byte of EPROM is programmed using the following sequence:
– set ELAT
– write data to the desired EPROM address
– set EPGM for time t_PROG
– clear EPGM/ELAT
7-modes
MOTOROLA
Modes of Operation and Pin Descriptions
For More Information On This Product,
Go to: www.freescale.com
MC68HC05X4 Rev 1.0
19