MC68HC705P9CS datasheet(39/160 Pages) FREESCALE

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Memory

EPROM/OTPROM

MC68HC705P9 — Rev. 4.0

Technical Data

MOTOROLA

Memory

Take the following steps to program a byte of EPROM/OTPROM:

1. Apply 16.5 V to the IRQ/VPP pin.

2. Set the LATCH bit.

3. Write to any EPROM/OTPROM address.

4. Set the EPGM bit for a time, tEPGM, to apply the programming

voltage.

5. Clear the LATCH bit.

3.6.1.2 Bootloader ROM

The bootloader ROM, located at addresses $1F00–$1FEF, contains

routines for copying an external EPROM to the on-chip

EPROM/OTPROM.

The bootloader copies to the following EPROM/OTPROM addresses:

•

$0020–$004F

•

$0100–$0900

•

$1FF0–$1FFF

The addresses of the code in the external EPROM must match the

MC68HC705P9 addresses. The bootloader ignores all other addresses.

Figure 3-4 shows the circuit for downloading to the on-chip

EPROM/OTPROM from a 2764 EPROM. The bootloader circuit includes

an external 12-bit counter to address the external EPROM. Operation is

fastest when unused external EPROM addresses contain $00. The

bootloader function begins when a rising edge occurs on the RESETpin

while the VPP voltage is on the IRQ/VPP pin, and the PD7/TCAP pin is at

logic one.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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