MC68HC705P6A Datasheet, PDF (87/130 Pages) Motorola, Inc – HCMOS Microcontroller Unit

EPROM
Programming from an External Memory Device
10.8 Programming from an External Memory Device
In this programming mode, PC5 must be connected to V_SS. PC4 and
PC3 are used to select the programming mode. The programming circuit
shown in Figure 10-2 uses an external 12-bit counter to address the
memory device containing the code to be copied. This counter requires
a clock and a reset function. The 12-bit counter can address up to
4 Kbytes of memory, which means that a port pin has to be used to
address the remaining 4 K of the 8-K memory space.
The following procedure explains how to use the programming circuit
shown in Figure 10-2 to copy a user program from an external memory
device into the MCU’s EPROM:
1. Program a 2764-type EPROM device with the desired instructions
and data. Code programmed into the 2764 must appear at the
same addresses desired in the MC68HC705P6A. Therefore, the
page zero code must start at $0020 and end at $004F, the main
body of code must start at $0100 and end at $12FF, and the user
vectors must start at $1FF0 and end at $1FFF.
NOTE: The MOR data must appear at $1EFF and $1F00.
2. Install the programmed 2764 device into the programming circuit.
3. Install the MC68HC705P6A to be programmed into the
programming circuit.
4. Set the PROGRAM and/or VERIFY switches for the desired
operation (an open switch is the active state) and close the
RESET switch to hold the MCU in reset.
5. Make sure that the V_PP source is OFF.
6. Apply the V_DD source to the programming circuit.
7. Apply the V_PP source to the programming circuit.
8. Open the RESET switch to allow the MCU to come out of reset
and begin execution of the software in its internal bootloader
ROM.
MC68HC705P6A — Rev. 2.0
MOTOROLA
EPROM
Advance Information
87