Datasheet

Operating Modes and Memory

MC68HC711D3 Data Sheet, Rev. 2.1

22 Freescale Semiconductor

If this mode is entered out of reset, the EPROM is located at $7000–$7FFF and vector accesses are from

external memory. To be in expanded-multiplexed mode with EPROM located at $F000–$FFFF, it is

necessary to start in single-chip mode, executing out of EPROM, and then set the MDA bit of the HPRIO

NOTE

R/W

, AS, and the high-order address bus (port B) are inputs in single-chip

mode. These inputs may need to be pulled up so that off-chip accesses

cannot occur while the MCU is in single-chip mode.

2.2.3 Special Bootstrap Mode (BOOT)

This special mode is similar to single-chip mode. The resident bootloader program contains a 256-byte

program in a special on-chip read-only memory (ROM). The user downloads a small program into

on-board RAM using the SCI port. Program control is passed to RAM when an idle line of at least four

characters occurs. In this mode, all interrupt vectors are mapped to RAM (see Table 2-2), so that the user

can set up a jump table, if desired.

Bootstrap mode (BOOT) is entered out of reset if the voltage level on both MODA and MODB is low. The

programming aspect of bootstrap mode, used to program the one-time programmable ROM (OTPROM)

through the MCU, is entered automatically if IRQ

is low and programming voltage is available on the V

pin. IRQ

should be pulled up while in reset with MODA and MODB configured for bootstrap mode to

prevent unintentional programming of the EPROM.

This versatile mode (BOOT) can be used for test and diagnostic functions on completed modules and for

programming the on-board PROM. The serial receive logic is initialized by software in the bootloader

ROM, which provides program control for the SCI baud rate and word format. Mode switching to other

modes can occur under program control by writing to the SMOD and MDA bits of the HPRIO register. Two

special bootloader functions allow either an immediate jump-to-RAM at memory address $0000 or an

immediate jump-to-EPROM at $F000.

Table 2-2. Bootstrap Mode Jump Vectors

Address Vector

00C4 SCI

00C7 SPI

00CA Pulse accumulator input edge

00CD Pulse accumulator overflow

00D0 Timer overflow

00D3 Timer output compare 5/input capture 4

00D6 Timer output compare 4

00D9 Timer output compare 3

00DC Timer output compare 2

00DF Timer output compare 1

00E3 Timer input capture 3

00E5 Timer input capture 2

00E8 Timer input capture 1