HC05 datasheet(26/232 Pages) MOTOROLA

26 / 232 page

MOTOROLA

2-2

MC68HC05X16

Rev. 1

MODES OF OPERATION AND PIN DESCRIPTIONS

2.1.2

Bootstrap mode

To place the part in bootstrap mode, the following conditions must be met during transition of the

RESET pin from low to high:

1) IRQ pin at 2xVDD OR MDS pin at VDD

2) TCAP1 pin at VDD

3) TCAP2 pin at VSS

PD4 and PD3 are connected according to the values given in Table 2-1 to select the device’s

function from the following three functions:

•

Execute serial RAM loader program

•

Jump to RAM + 1

•

Jump to any address

If the SEC bit in the option register is set, on ﬁrst entering bootstrap mode the RAM and the EEPROM

are completely erased. The option register which contains the security bit is erased last, before any

program can be executed. The bootstrap software is implemented in the following locations:

•

RAM load and execute from $03B0 to $03FD

•

Vectors and program select from $7F80 to $7FEF

Figure 2-1 Bootstrap mode function selection ﬂow chart

Save PD in RAM. Erase

whole EEPROM + RAM

and check EPROM +

SEC bit.

ENTRY

PD4 set

PD3 set

SEC bit active?

Jump to address

deﬁned by ports A, B

and C.

YES

PD4 set

Reserved for

Motorola use.

Serial RAM bootstrap

loader.

Jump to RAM + 1.

YES

HC05 Datasheet(PDF) 26 Page - Motorola, Inc

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