Datasheet

M16C/2
6
Programming Flash Memory via Flash-Over-USB™
REU05B0042-0100Z June 2003
Page 2 of 8
program allows asynchronous or synchronous serial programming of the user area of the flash and can only be
changed by using Parallel I/O Mode.
Renesas provides a Windows
 based program, Flash-Over-USB™ (FoUSB), to download code to M16C/26
MCUs. FoUSB Programmer is used along with the USB-Monitor (see Figure 3) for reprogramming the flash
memory of a M16C/26 microcontroller over USB (Universal Serial Bus).
Figure 2 M16C/26 Flash Memory Map
Host PC running
FoUSB Programmer
Figure 3 M16C System Connectivity for FoUSB Programmer
3.0 Hardware Requirements for Synchronous Serial Programming
The CNVSS pin on the M16C MCU is the primary control line that determines whether the user area or the boot
area of the flash memory is accessed after reset is released. 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 synchronous serial rewrite program
in the boot area of the flash, the CNVSS pin has to be held high. The operation uses the four UART1 pins of the
MCU: CLK1 (P6
5
), RxD1 (P66), TxD1 (P6
7
) and RTS1 (P6
4
). The CLK1 pin is the transfer clock input pin through
which a 1MHz clock is fed to the MCU from the USB monitor for synchronous data input to the RxD1 pin. The