APPLICATION NOTE
M16C/62
Programming the M16C/62 Flash in Asynchronous Serial Mode
1.0 Abstract
The following article describes using an asynchronous serial port and the FlashStart application to program the
user flash memory of the M16C/62 series of microcontrollers. This is referred to in the M16C/62 data sheets as
the 鈥淪tandard Serial I/O Mode 2鈥?method of flash programming.
2.0 Introduction
The Renesas M16C/62 series of microcontrollers is a 16-bit family of MCUs, based on Renesas鈥?popular M16C
CPU core. These parts provide high memory efficiency, power-saving ability, low noise emission, and improved
noise immunity. The flash versions of the device contain flash memory that can be rewritten with a single voltage.
The M16C/62 flash can be programmed using one of three methods: Parallel I/O Mode, Standard Serial I/O
Mode, and CPU Rewrite Mode. Standard Serial I/O Mode can be further divided into a synchronous mode
(Standard Serial I/O Mode 1) and an asynchronous mode (Standard Serial I/O Mode 2). The flash memory is
divided into two major blocks, a user program area and a boot ROM area. The user program area is for the
normal application program and data. Any program in the boot ROM area is accessed only when a special
hardware reset sequence is initiated. This boot ROM area has a control program stored in it when shipped from
the factory. The program allows asynchronous or synchronous serial programming of the user area of the flash.
Changes to the boot area of the flash can only be made using Parallel I/O Mode.
Renesas provides a Windows
錚?/div>
based program, FlashStart, to serially download code (in S-record format) to
M16C/62 MCUs. The website for downloading the program is listed in section 5.0 Reference
3.0 Hardware Requirements for Asynchronous Serial Programming
The CNVSS pin on the microcontroller is the primary control line that determines whether the user area of the
flash or the boot area is accessed after the release of a reset. If the CNVSS pin is low the device will always
access the user flash area and will start in single chip mode. To execute the asynchronous serial rewrite program
in the boot area of the flash, the pins listed below must be connected as shown when a reset is performed (either
during power-up of the microcontroller or by forcing the Reset line low and then setting it high). Figure 1 shows a
typical connection.
REU05B0013-0100Z
June 2003
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