Freescale Semiconductor 802.15.4 manual Safe Mode Boot

2.1.2 Use Case Two

In this use case, users push a button on the board to enable firmware upload. MC908HCS08GB60(1)/MC13192

BApplication

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oNVM

t

l 802.15.4 MAC o

a

d 802.15.4 PHY e

r Device Driver GPIO

1)Or MC908HCS08GT60

I/O

User Interface

Push Buttons

S101 S102 S103 S104

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

2-2 Embedded Bootloader Reference Manual, Rev 0.0 Freescale Semiconductor