Freescale Semiconductor 802.15.4/Zigbee, Reference Manual, Page: 14 / 66

2-2 Embedded Bootloader Reference Manual, Rev 0.0 Freescale Semiconductor
2.1.2 Use Case Two
In this use case, users push a button on the board to enable firmware upload.
MC908HCS08GB60
(1)
/MC13192
B Application
o
o NVM
t
l 802.15.4 MAC
o
a User Interface
d 802.15.4 PHY Push Buttons
e I/O
r Device Driver GPIO S101 S102 S103 S104
1)
Or MC908HCS08GT60
Figure 2 Application Supporting an I/O Interface
2.1.3 Safe Mode Boot
The Safe Mode Boot Mode is a special startup mode where the Embedded Bootloader boots using safe
system settings thereby resetting the system to a known (default) state.
The Safe Mode Boot can be used to disable the detection of an invalid/malfunctioning application due to
items such as code errors, corrupt NVM data, or internal flash programming errors among others. All the
NVM memory (except production data and MAC address) is completely erased.
The Safe Mode Boot can also be used to upload firmware without first calling the
Enable_Download_Firmware() function. This could be useful if the use cases (as shown in
Section 2.1,
Upload Firmware ) are not applicable.
Users must perform the following steps to conduct a Safe Mode Boot.
1. Power off the board
2. Disconnect RS232 UART cable (if the RS232 UART interface is used)
3. Short UART TX and RX (pin 2-3) (This works even though the 802.15.4/Zigbee application does not
use the UART interface.)
4. Power up again. All LEDs are off.
5. Wait until LED1 goes on (< 1 second)
6. Power off the board