HC705P6AGRSSLASHD datasheet(87/134 Pages) NXP

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General Release Specification

EPROM Bootloader

MC68HC705P6A — Rev. 1.0

General Release Specification

EPROM

10.7 EPROM Bootloader

Three port pins are associated with bootloader control functions: PC3,

PC4, and PC6. Table 10-2 summarizes their functionality.

10.8 Programming from an External Memory Device

In this programming mode, PC5 must be connected to VSS. 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.

Table 10-2. Bootloader Control Pins

PC6

PC4

PC3

Mode

Program/Verify

Verify Only

Dump MCU EPROM to Port A

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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