On-Board Programming Modes; Boot Mode - Hitachi H8S/2646 Hardware Manual

Hitachi 16-bit single-chip microcomputer h8s/2646 series

Table of Contents

Bit 7: PDWND

Transition to flash memory power-down mode enabled

Transition to flash memory power-down mode disabled

Bits 6 to 0—Reserved: These bits always read 0.

On-Board Programming Modes

When pins are set to on-board programming mode and a reset-start is executed, a transition is

made to the on-board programming state in which program/erase/verify operations can be

performed on the on-chip flash memory. There are two on-board programming modes: boot mode

and user program mode. The pin settings for transition to each of these modes are shown in table

20-5. For a diagram of the transitions to the various flash memory modes, see figure 20-2.

Table 20-5 Setting On-Board Programming Modes

User program mode

When boot mode is used, the flash memory programming control program must be prepared in the

host beforehand. The SCI channel to be used is set to asynchronous mode.

When a reset-start is executed after the LSI's pins have been set to boot mode, the boot program

built into the LSI is started and the programming control program prepared in the host is serially

transmitted to the LSI via the SCI. In the LSI, the programming control program received via the

SCI is written into the programming control program area in on-chip RAM. After the transfer is

completed, control branches to the start address of the programming control program area and the

programming control program execution state is entered (flash memory programming is

The transferred programming control program must therefore include coding that follows the

programming algorithm given later.

The system configuration in boot mode is shown in figure 20-6, and the boot mode execution

procedure in figure 20-7.

Expanded mode

Single-chip mode

Expanded mode

Single-chip mode

(Initial value)