User Guide

6255/6255i6256/6256i (RM-19)

Baseband Description and Troubleshooting Nokia Customer Care

Flash Programming Indication

After connecting the flash prommer to the mobile terminal, the flash prommer sets the

MBUS line low to notify the MCU that the flash prommer is connected. This causes the

UEME reset state machine to perform a reset to the system by setting the PURX signal

low for 20ms.

During flash programming, the MBUS signal transmitted from the UEME to the flash

prommer is used as the clock for synchronous communication. This MBUS clock is also

supplied by the UEME to the D2800 processor, along with the MBUSRX signal. If the

MBUSRX signal is low, the MCU enters flash programming mode. To avoid accidental

entry into flash-programming mode, the MCU waits to get input data from the flash

prommer. If the timer expires without any data being received, the MCU continues the

boot sequence.

When the mobile terminal has entered flash programming mode, the flash prommer

writes an 8-bit password to the UEME to indicate that flash programming/

reprogramming is to take place. This 8-bit data is transmitted through the FBUSRX line

into a shift register inside the UEME. When the 8 bits have been shifted into the register,

the flash prommer generates a falling edge on the BSI line. This loads the shift register

content into a comparison register inside the UEME. If the 8 bits in the comparison

In order to avoid spurious loading of the register, the BSI signal is gated during UEME

master reset and during power up when the PURX is active (low). The BSI signal must not

change states during normal operation unless the battery is extracted. If the battery is

extracted, the BSI signal is pulled high.

Note: A falling edge is required to load the comparison register.

The UEME flash programming mode is valid until the MCU sets a bit in the UEME register

that indicates the end of flash programming. Setting this bit also clears the comparison

flash programming mode, the UEME watchdogs are disabled. Setting the bit indicating

the end of flash programming enables and resets the UEME watchdog timer to its default

value. Clearing the flash programming bit also causes the UEME to generate a reset to

the D2800 processor.

Flashing

Flash programming is done through the VPP, FBUSTX, FBUSRX, MBUS, and BSI signals.

When the mobile terminal enters flash programming mode, the prommer indicates that

flash programming will take place by writing an 8-bit password to the UEME. The

prommer sets the BSI value to “1” and then uses FBUSRX for writing and MBUS for

clocking. The BSI is then set back to “0”.

The MCU uses the FBUSTX signal to indicates to the prommer that it has been noticed.

After this, the MCU reports the ID type to the D2800 processor and is ready to receive

the secondary boot code to its internal SRAM.