HC705RC16GRSSLASHD datasheet(84/120 Pages) NXP

84 / 120 page

EPROM

General Release Specification

MC68HC705RC16 — Rev. 3.0

EPROM

10.4 Bootloader

This program (contained in an on-chip boot ROM) handles copying of

user code from an external EPROM into the on-chip EPROM. The

bootloader function does not have to be done from an external EPROM,

but can be done from a host.

10.4.1 Bootloader Functions

Two pins are used to select the bootloader function. These pins are PC1

and PB5. PC1 is normally a SYNC pin, which is used to synchronize the

MCU to an off-chip source that is driving EPROM data into the MCU. The

programmer/host interface is shown in Figure 10-1.

Figure 10-1. Programmer Interface to Host

If an external EPROM is used, this pin (PC1) must be connected to V

PB5 is used to select between program/verify or verify-only modes. Two

other pins, PB2 and IRO, are used to drive the VERF LED and the

PROG LED respectively. The programming modes are shown in Table

10-1.

The bootloader programming board 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 two port pins have to be used to address the extra memory space.

Table 10-1. Bootloader Functions

PC1

PB5

Mode

SYNC

Program/Verify

SYNC

Verify Only

CLK (OUT)

SYNC (IN)

DATA IN

DATA READ

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

HC705RC16GRS/D Datasheet(PDF) 84 Page - NXP Semiconductors