Part Programming
AT89STK-03 Hardware User Guide
3-21
7609B–SCR–11/06
3.3
Bootloader DSU
The DSU bootloader fixes a USB bug present in the DRV bootloader. Therefore the
DSU bootloader has the same features as the DRV bootloader.
Ensure you are familiar with the DSU bootloader datasheet before programming the
part.
Configure the MCU demonstration board following Table 2-2 on page 9.
3.3.1
ISP Mode
CRAM version
The bootloader enters automatically in ISP mode with this version after power up or res-
set sequences and waits for commands from FLIP as there is no code available to run.
When the bootloader is running in ISP mode, the ALE led blinks.
FLASH version
The ISP mode must be invoked manually by holding down the ISP switch (P3.7=0) dur-
ing power up or reset sequences. When the bootloader is running in ISP mode, the ALE
led blinks.
3.3.2
Execution mode
CRAM version
The execution mode must be invoked manually from FLIP. ALE Led remains on perma-
nently during this mode.
FLASH version
The execution mode does not request specific action. The application code runs auto-
matically after power up or reset sequence. ALE Led remains on permanently during
this mode.
Notes:
1. The external E2PROM works only with the PLCC68 package. It enables to get a flash
equivalent solution as the PLCC68 is only available in CRAM version. For the others
packages, order the appropriate part as the E2PROM is implemented inside the
package.
2. The programming of internal or external E2PROM is automatically handled by the
bootloader
